DEI	12 Months Ended
DEI	Dec. 31, 2017 shares
Document Information [Abstract]
Document Type	20-F
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2017
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Period Focus	FY
Entity Registrant Name	Verona Pharma PLC
Entity Central Index Key	0001657312
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	No
Number of shares outstanding (in shares)	105,017,400

CONSOLIDATED STATEMENT OF FINANCIAL POSITION - GBP (£)	Dec. 31, 2017	Dec. 31, 2016
Non-current assets:
Goodwill	£ 441,000	£ 441,000
Intangible assets	1,969,000	1,877,000
Property, plant and equipment	16,000	14,000
Total non-current assets	2,426,000	2,332,000
Current assets:
Prepayments and other receivables	1,810,000	2,959,000
Current tax receivable	5,006,000	1,067,000
Short term investments	48,819,000	0
Cash and cash equivalents	31,443,000	39,785,000
Total current assets	87,078,000	43,811,000
Total assets	89,504,000	46,143,000
Capital and reserves attributable to equity holders:
Share capital	5,251,000	2,568,000
Share premium	118,862,000	58,526,000
Share-based payment reserve	5,022,000	2,103,000
Accumulated loss	(49,254,000)	(28,728,000)
Total equity	79,881,000	34,469,000
Current liabilities:
Derivative financial instrument	1,273,000	7,923,000
Trade and other payables	7,154,000	2,823,000
Tax payable—U.S. Operations	169,000	126,000
Total current liabilities	8,596,000	10,872,000
Non-current liabilities:
Assumed contingent obligation	875,000	802,000
Deferred income	152,000	0
Total non-current liabilities	1,027,000	802,000
Total equity and liabilities	£ 89,504,000	£ 46,143,000

CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Profit or loss [abstract]
Research and development costs	£ (23,717)	£ (4,522)	£ (7,270)
General and administrative costs	(6,039)	(2,498)	(1,706)
Operating loss	(29,756)	(7,020)	(8,976)
Finance income	7,018	1,841	45
Finance expense	(2,465)	(794)	(73)
Loss before taxation	(25,203)	(5,973)	(9,004)
Taxation — credit	4,706	954	1,509
Loss for the year	(20,497)	(5,019)	(7,495)
Other comprehensive income / (loss) :
Exchange differences on translating foreign operations	(29)	43	4
Total comprehensive loss attributable to owners of the Company	£ (20,526)	£ (4,976)	£ (7,491)
Loss per ordinary share — basic and diluted (pence per share)	£ (23.4)	£ (15.0)	£ (37.1)

CONSOLIDATED STATEMENT OF CASH FLOWS £ in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017 GBP (£)	Dec. 31, 2016 GBP (£)	Dec. 31, 2015 GBP (£)
Cash used in operating activities:
Loss before taxation	£ (25,203)	£ (5,973)	£ (9,004)
Finance income	(7,018)	(1,841)	(45)
Finance expense	2,465	794	73
Share-based payment charge	2,919	577	399
Decrease / (increase) in prepayments and other receivables	(161)	(1,809)	59
Increase in trade and other payables	5,363	1,068	1,274
Depreciation of property, plant and equipment	7	10	10
Loss on disposal of property, plant and equipment	0	3	0
Loss on disposal of intangible assets	0	0	135
Amortization of intangible assets	116	52	43
Cash used in operating activities	(21,512)	(7,119)	(7,056)
Cash inflow from taxation	816	1,533	700
Net cash used in operating activities	(20,696)	(5,586)	(6,356)
Cash flow from investing activities:
Interest received	128	87	51
Purchase of plant and equipment	(9)	(13)	(1)
Payment for patents and computer software	(208)	(115)	(142)
Transfer to short term investments	(54,465)	0	0
Maturity of short term investments	5,085	0	0
Net cash used in investing activities	(49,469)	(41)	(92)
Cash flow from financing activities:
Gross proceeds from issue of shares and warrants	0	44,750	0
Gross proceeds from the April 2017 Global Offering	70,032	0
Transaction costs on issue of shares and warrants	0	(2,910)	0
Transaction costs on April 2017 Global Offering	(6,786)	(636)	0
Net cash generated from financing activities	63,246	41,204	0
Net (decrease) / increase in cash and cash equivalents	(6,919)	35,577	(6,448)
Cash and cash equivalents at the beginning of the year	39,785	3,524	9,968
Effect of exchange rates on cash and cash equivalents	(1,423)	684	4
Cash and cash equivalents at the end of the period	£ 31,443	£ 39,785	£ 3,524

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - GBP (£) £ in Thousands	Total	Share Capital	Share Premium	Share-based Expenses	Total Accumulated Losses
Beginning balance at Dec. 31, 2014	£ 12,526	£ 1,010	£ 26,650	£ 1,127	£ (16,261)
Loss for the year	(7,495)				(7,495)
Exchange differences on translating foreign operations	4				4
Total comprehensive loss for the period	(7,491)				(7,491)
Share-based payments	399			399
Ending balance at Dec. 31, 2015	5,434	1,010	26,650	1,526	(23,752)
Loss for the year	(5,019)				(5,019)
Exchange differences on translating foreign operations	43				43
Total comprehensive loss for the period	(4,976)				(4,976)
New share capital issued	35,707	1,556	34,151
Transaction costs on share capital issued	(2,325)		(2,325)
Share options exercised during the period	52	2	50
Share-based payments	577			577
Ending balance at Dec. 31, 2016	34,469	2,568	58,526	2,103	(28,728)
Loss for the year	(20,497)				(20,497)
Exchange differences on translating foreign operations	(29)				(29)
Total comprehensive loss for the period	(20,526)				(20,526)
New share capital issued	70,325	2,677	67,648
Transaction costs on share capital issued	(7,453)		(7,453)
Share options exercised during the period	147	6	141
Share-based payments	2,919			2,919
Ending balance at Dec. 31, 2017	£ 79,881	£ 5,251	£ 118,862	£ 5,022	£ (49,254)

General information	12 Months Ended
General information	Dec. 31, 2017
Disclosure of notes and other explanatory information [Abstract]
General information	General information Verona Pharma plc and its subsidiaries (the "Company") are a clinical-stage biopharmaceutical group focused on developing and commercializing innovative therapeutics for the treatment of respiratory diseases with significant unmet medical needs. The Company is a public limited company, which is dual listed on the Alternative Investment Market of the London Stock Exchange and on April 27, 2017, American Depositary Shares began trading on Nasdaq Global Market. The company is incorporated and domiciled in the United Kingdom. The address of the registered office is 1 Central Square, Cardiff, CF10 1FS, United Kingdom. The Company has two subsidiaries, Verona Pharma Inc. and Rhinopharma Limited ("Rhinopharma"), both of which are wholly owned. On February 10, 2017 the Company effected a 50-for-1 consolidation of its shares. All references to ordinary shares, options and warrants, as well as share, per share and related information in these consolidated financial statements have been adjusted to reflect the consolidation as if it had occurred at the beginning of the earliest period presented. On April 26, 2017, the Company announced the closing of its global offering of an aggregate of 47,399,001 new ordinary shares, consisting of the initial public offering in the United States of 5,768,000 American Depositary Shares (“ADSs”) at a price of $13.50 per ADS and the private placement in Europe of 1,255,001 ordinary shares at a price of £1.32 per ordinary share, for gross proceeds of $80 million (the “Global Offering”). Each ADS offered represents eight ordinary shares of the Company. The ordinary shares offered were allotted and issued in a concurrent private placement in Europe and other countries outside of the United States and Canada. In addition, the Chairman of Verona Pharma’s board of directors, Dr David Ebsworth, and an existing shareholder agreed to subscribe for 254,099 new ordinary shares at a price of £1.32 per ordinary share in a shareholder private placement separate from the Global Offering (the “Shareholder Private Placement”), contingent on and concurrent with the Global Offering and generating additional gross proceeds of £0.3 million. On May 15 and May 23, 2017, pursuant to the Global Offering, the underwriters purchased an additional 733,738 ADSs, representing 5,869,904 ordinary shares, at a price of $13.50 per ADS, for additional gross proceeds of $9.9 million bringing the total gross proceeds in the Global Offering to $89.9 million (£70.0 million). Including the Shareholder Private Placement, the total gross proceeds of the capital raising amounted to $90.3 million (£70.3 million). The ADSs began trading on the Nasdaq Global Market under the ticker symbol “VRNA” on April 27, 2017. Verona Pharma’s ordinary shares continue to trade on the AIM market of the London Stock Exchange (“AIM”) under the symbol “VRP”.

Accounting policies

12 Months Ended

Dec. 31, 2017

Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]

Accounting policies

A summary of the principal accounting policies, all of which have been applied consistently throughout the year, is set out below.

Basis of preparation

The consolidated financial statements of the Company have been prepared in accordance with International Financial Reporting Standards ("IFRSs") as issued by the International Accounting Standards Board and IFRS Interpretations Committee and with the Companies Act 2006 applicable to companies reporting under IFRS.

The consolidated financial statements have been prepared under the historical cost convention, with the exception of derivative financial instruments which have been measured at fair value.

The preparation of financial statements in conformity with IFRS requires the use of certain critical accounting estimates. It also requires management to exercise its judgement in the process of applying the Company's accounting policies. The areas involving a higher degree of judgement or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are disclosed in note 4.

Going concern

During the year ended December 31, 2017, the Company had a loss of £20.5 million (2016: £5.0 million). As of December 31, 2017, the Company had net assets of £79.9 million (2016: £34.5 million) of which £80.3 million (2016: £39.8 million) was cash and cash equivalents and short term investments.

The operation of the Company is currently being financed from funds that the Company raised from share placings. On May 2nd, 2017, the company raised $89.9 million (£70 million) from the initial public offering in the United States. On July 29, 2016, the Company raised gross proceeds of £44.7 million from a placing, subscription and open offer (the "July 2016 Placement"). These funds are expected to be used primarily to support the development of RPL554 in chronic obstructive pulmonary disease ("COPD"), other chronic respiratory diseases as well as corporate and general administrative expenditures.

The Directors believe that the Company has sufficient funds to complete the current clinical trials, to cover corporate and general administration costs and for it to comply with all commitments for at least 12 months from the end of the reporting period and, accordingly, are satisfied that the going concern basis remains appropriate for the preparation of these consolidated financial statements.

Business combination

The Company applies the acquisition method to account for business combinations. The consideration transferred for the acquisition of a subsidiary is the fair value of the assets transferred, the liabilities incurred to the former owners of the acquiree and the equity interests issued by the Company. The consideration transferred includes the fair value of any asset or liability resulting from a contingent consideration arrangement and the fair value of any pre-existing equity interest in the subsidiary. The excess of the cost of acquisition over the fair value of the Company's share of the identifiable net assets acquired is recorded as goodwill. Goodwill arising on acquisitions is capitalized and is subject to an impairment review, both annually and when there are indications that the carrying value may not be recoverable.

Identifiable assets acquired and liabilities and contingent liabilities assumed in a business combination are measured initially at their fair values at the acquisition date. Acquisition-related costs are expensed as incurred and included in administrative expenses.

Basis of consolidation

These consolidated financial statements include the accounts of Verona Pharma plc and its wholly owned subsidiaries Verona Pharma, Inc. and Rhinopharma. The acquisition method of accounting was used to account for the acquisition of Rhinopharma.

Inter-company transactions, balances and unrealized gains on transactions between group companies are eliminated.

Verona Pharma Inc. and Rhinopharma adopt the same accounting policies as the Company.

Foreign currency translation

Items included in the Company's consolidated financial statements are measured using the currency of the primary economic environment in which the Entity operates ("the functional currency"). The consolidated financial statements are presented in pounds sterling ("£"), which is the functional and presentational currency of the Company and the presentational currency of the Company.

Transactions in foreign currencies are recorded using the rate of exchange ruling at the date of the transaction. Monetary assets and liabilities denominated in foreign currencies are translated using the rate of exchange ruling at the balance sheet date and the gains or losses on translation are included in the Consolidated Statement of Comprehensive Income. Non-monetary items that are measured in terms of historical cost in a foreign currency are translated using the exchange rates at the dates of the original transactions. Non-monetary items measured at fair value in a foreign currency are translated using the exchange rates at the date when the fair value was determined.

The assets and liabilities of foreign operations are translated into pounds sterling at the rate of exchange ruling at the balance sheet date. Income and expenses are translated at weighted average exchange rates for the period. The exchange differences arising on translation for consolidation are recognized in Other Comprehensive Income.

Cash and cash equivalents

Cash and cash equivalents includes cash in hand, deposits held at call with banks and other short-term highly liquid investments with original maturities of three months or less.

Deferred taxation

Deferred tax is provided in full, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated financial statements. Deferred tax is determined using tax rates (and laws) that have been enacted or substantially enacted by the balance sheet date and expected to apply when the related deferred tax is realized or the deferred liability is settled.

Deferred tax assets are recognized to the extent that it is probable that the future taxable profit will be available against which the temporary differences can be utilized.

Research and development costs

Capitalization of expenditure on product development commences from the point at which technical feasibility and commercial viability of the product can be demonstrated and the Company is satisfied that it is probable that future economic benefits will result from the product once completed. No such costs have been capitalized to date, given the early stage of the Company's product candidate development.

Expenditure on research and development activities that do not meet the above criteria is charged to the Consolidated Statement of Comprehensive Income as incurred.

Property, plant and equipment

Property, plant and equipment are stated at cost, net of depreciation and any provision for impairment. Cost includes the original purchase price of the asset and the costs attributable to bringing the asset to its working condition for its intended use. Depreciation is calculated so as to write off the cost less their estimated residual values, on a straight-line basis over the expected useful economic lives of the assets concerned. The principal annual periods used for this purpose are:



Computer hardware	3 years
Office equipment	5 years

Intangible assets and goodwill


(a)	Goodwill

Goodwill arises on the acquisition of subsidiaries and represents the excess of the consideration transferred over the fair value of the identifiable net assets acquired.


(b)	Patents

Patent costs associated with the preparation, filing, and obtaining of patents are capitalized and amortized on a straight-line basis over the estimated useful lives of the patents of ten years.


(c)	Computer software

Amortization is calculated so as to write off the cost less estimated residual values, on a straight-line basis over the expected useful economic life of two years.


(d)	In-process research & development ("IPR&D")

IP R&D assets acquired through business combinations which, at the time of acquisition, have not reached technical feasibility are recognized at fair value. The amounts are capitalized and are not amortized but are subject to impairment testing until completion, abandonment of the projects or when the research findings are commercialized through a revenue generating project. The Company determines whether intangible assets (including goodwill) are impaired on an annual basis and this requires the estimation of the higher of fair value less costs of disposal and value in use. Upon successful completion or commercialization of the relevant project, IP R&D will be reclassified to developed technology. The Company will make a determination as to the then useful life of the developed technology, generally determined by the period in which the substantial majority of the cash flows are expected to be generated, and begin amortization. In case of abandonment the asset will be impaired.

Impairment of intangible assets, goodwill and non-financial assets

Goodwill and intangible assets that have an indefinite useful life and intangible assets not ready to use are not subject to amortization. These assets are tested annually for impairment or more frequently if impairment indicators exist. Non-financial assets that are subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. An impairment loss is recognized for the amount by which the asset's carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset's fair value (less costs of disposal) and value in use.

For the purpose of assessing impairment, assets are grouped at the lowest levels for which there are separately identifiable cash flows, which are largely independent of the cash flows from other assets or group of assets (cash generating units "CGUs").

Goodwill is allocated to CGUs for the purpose of impairment testing. The allocation is made to those CGUs or groups of CGUs that are expected to benefit from the business combination in which the goodwill arose. The units or group of units are identified at the lowest level at which goodwill is monitored for internal management purposes, being the operating segments.

The Company is a single cash generating unit. Goodwill that arose on the acquisition of Rhinopharma has been thus allocated to this single CGU. IP R&D is tested for impairment at this level as well, since it is the lowest level at which independent cash flows can be identified.

Non-financial assets, other than goodwill, that have been previously impaired are reviewed for possible reversal of the impairment at each subsequent reporting date.

Employee Benefits


(a)	Pension

The Company operates a defined contribution pension scheme for UK employees. Contributions payable for the year are charged to the Consolidated Statement of Comprehensive Income. The contributions are recognized as employee benefit expense when they are due. Differences between contributions payable in the year and contributions actually paid are shown as either accruals or prepayments in the Consolidated Statement of Financial Position. The Company has no further payment obligation once the contributions have been paid.


(b)	Bonus plans

The Company recognizes a liability and an expense for bonus plans if contractually obligated or if there is a past practice that has created a constructive obligation.

Share-based payments

The Company operates a number of equity-settled, share-based compensation schemes. The fair value of share-based payments under such schemes is expensed on a straight-line basis over the vesting period, based on the Company's estimate of shares that will eventually vest.

Where equity settled transactions are entered into with third party service providers, fair value is determined by reference to the value of the services provided in lieu of payment. The expense is measured based on the services received at the date of receipt of those services and is charged to the Consolidated Statement of Comprehensive Income over the period for which the services are received and a corresponding credit is made to reserves. For other equity-settled transactions fair value is determined using the Black-Scholes model and requires several assumptions and estimates as disclosed in note 16.

Provisions

Provisions are recognized when the Company has a present legal or constructive obligation as a result of past events, it is probable that an outflow of resources will be required to settle the obligation, and the amount can be reliably estimated. Provisions are measured at the present value of the expenditures expected to be required to settle the obligation using a pre-tax rate that reflects current market assessments of the time value of money and the risks specific to the obligation.

Assumed contingent obligation related to the business combinations

On September 19, 2006, the Company acquired Rhinopharma for a total consideration of £1.52 million payable in ordinary shares. In addition, the Company assumed certain contingent obligations owed by Rhinopharma to Vernalis under an assignment and license agreement (the "assumed contingent consideration") following the sale of IP by Vernalis to Rhinopharma. Pursuant to the agreement Vernalis (i) assigned to the Company all of its rights to certain patents and patent applications relating to RPL554 and related compounds (the "Vernalis Patents") and (ii) granted to the Company an exclusive, worldwide, royalty-bearing license under certain Vernalis know-how to develop, manufacture and commercialize products (the "Licensed Products") developed using Vernalis Patents, Vernalis know-how and the physical stock of certain compounds.

The assumed contingent obligation comprises (a) a milestone payment on obtaining the first approval of any regulatory authority for the commercialization of a Licensed Product; (b) low to mid single digit royalties based on the future sales performance of all Licensed Products; and (c) a portion equal to a midtwenty percent of any consideration received from any sub-licensees for the Vernalis Patents and for Vernalis know-how. On the date of acquisition the fair value of the assumed contingent obligation was estimated as the expected value of the milestone payment, royalty payments and sub-license payments, based on an assessment of the probability of success using standard market probabilities for respiratory drug development. The risk-weighted value of the assumed contingent arrangement was then discounted back to its net present value applying an effective interest rate of 12%. The initial fair value of the assumed contingent obligation as of December 31, 2006 was deemed to be insignificant at the date of the acquisition, so it was not recorded.

The amount of royalties payable under the agreement is based on the future sales performance of certain products, and so the total amount payable is unlimited. The level of sales that may be achieved under the

agreement is difficult to predict and subject to estimate, which is inherently uncertain. The value of this assumed contingent obligation is measured at amortized cost using the effective interest rate method, and is re-measured for changes in estimated cash flows, when the probability of success changes. The assumed contingent obligation is accounted for as a liability, and any adjustments made to the value of the liability will be recognized in the Consolidated Statement of Comprehensive Income for the period.

Government and other grants

The Company may receive government, regional or charitable grants to support its research efforts in defined projects where these grants provide for reimbursement of approved costs incurred as defined in the respective grants. Income in respect of such grants would include contributions towards the costs of research and development. Income would be recognized when costs under each grant are incurred in accordance with the terms and conditions of the grant and the collectability of the receivable is reasonably assured. Government, regional and charitable grants relating to costs would be deferred and recognized in the Consolidated Statement of Comprehensive Income over the period necessary to match them with the costs they are intended to compensate. When the cash in relation to recognized government, regional or charitable grants is not yet received the amount is included as a receivable on the Consolidated Statement of Financial Position.

Where the grant income is directly related to the specific items of expenditure incurred, the income would be netted against such expenditure. Where the grant income is not a specific reimbursement of expenditure incurred, the Company would include such income under "Other income" in the Consolidated Statement of Comprehensive Income. Grants or investment credits may be repayable if the Company successfully commercializes a relevant program that was funded in whole or in part by the grant or investment credit within a particular timeframe. Prior to successful commercialization, the Company would not make any provision for repayment.

Financial instruments — initial recognition and subsequent measurement

The Company classifies a financial instrument, or its component parts, as a financial liability, a financial asset or an equity instrument in accordance with the substance of the contractual arrangement and the definitions of a financial liability, a financial asset and an equity instrument.

The Company evaluates the terms of the financial instrument to determine whether it contains an asset, a liability or an equity component. Such components shall be classified separately as financial assets, financial liabilities or equity instruments.

A financial instrument is any contract that gives rise to a financial asset of one entity and a financial liability or equity instrument of another entity.


(a)	Financial assets, initial recognition and measurement and subsequent measurement

All financial assets not recorded at fair value through profit or loss, such as receivables and deposits, are recognized initially at fair value plus transaction costs. Financial assets carried at fair value through profit or loss are initially recognized at fair value, and transaction costs are expensed in the income statement.

The measurement of financial assets depends on their classification. Financial assets such as receivables and deposits are subsequently measured at amortized cost. The Company does not hold any financial assets at fair value through profit or loss or available for sale financial assets.


(b)	Financial liabilities, initial recognition and measurement and subsequent measurement

Financial liabilities are classified, at initial recognition, as financial liabilities at fair value through profit or loss, loans and borrowings, or payables, as appropriate. All financial liabilities are recognized initially at fair value and, in the case of loans and borrowings and payables, net of directly attributable transaction costs.

The measurement of financial assets and financial liabilities depends on their classification. Financial liabilities at fair value through profit or loss include financial liabilities held for trading and financial liabilities designated upon initial recognition as at fair value through profit or loss. These are subsequently measured at fair value with any gains or losses recognized in profit or loss. All other financial liabilities are measured at amortized cost using the effective interest method

The Company's financial liabilities include trade and other payables and derivative financial instruments.

Derivatives are initially recognized at fair value on the date a derivative contract is entered into and are subsequently re-measured at fair value at the end of each reporting date. The Company holds only one type of derivative financial instrument, the warrants, as explained in Note 2.15.

The full fair value of the derivative is classified as a non-current liability when the warrants are exercisable in more than 12 months and as a current liability when the warrants are exercisable in less than 12 months.

Changes in fair value of a derivative financial liability when related to a financing arrangement are recognized in the Consolidated Statement of Comprehensive Income within Finance income or Finance expense. Fair value gains or losses on derivatives used for non-financing arrangements are recognized in other operating income or expense.

Warrants

Warrants issued by the Company to investors as part of a share subscription are compound financial instruments where the warrant meets the definition of a financial liability.

The financial liability component is initially measured at fair value in the Consolidated Statement of Financial Position. Equity is measured at the residual between the subscription price for the entire instrument and the liability component. The financial liability component is remeasured depending on its classification. Equity is not remeasured.

Short Term Investments

Short term investments include fixed term deposits held at banks with original maturities of more than three months but less than a year. They are classified as loans and receivables and are measured at amortized cost using the effective interest method.

Transaction costs

Qualifying transaction costs might be incurred in anticipation of an issuance of equity instruments and may cross reporting periods. The entity defers these costs on the balance sheet until the equity instrument is recognized. Deferred costs are subsequently reclassified as a deduction from equity when the equity instruments are recognized, as the costs are directly attributable to the equity transaction. If the equity instruments are not subsequently issued, the transaction costs are expensed. Any costs not directly attributable to the equity transaction are expensed.

Transaction costs that relate to the issue of a compound financial instrument are allocated to the liability and equity components of the instrument in proportion to the allocation of proceeds. Where the liability component is held at fair value through profit or loss, the transaction costs are expensed to the Consolidated Statement of Comprehensive Income. For liabilities held at amortized cost, transaction costs are deducted from the liability and subsequently amortized. The amount of transaction costs accounted for as a deduction from equity in the period is disclosed separately in accordance with IAS 1.

Investments in subsidiaries

Investments in subsidiaries are shown at cost less any provision for impairment.

New standards, amendments and interpretations adopted by the Company

The following amendments have been adopted by the Company for the first time for the financial year beginning on or after 1 January, 2017. It did not materially impact the Company’s results:

· Annual Improvements to IFRS Standards 2014-2016 Cycle,

· Disclosure initiative - amendments to IAS 7, and

· Recognition of Deferred Tax Assets for Unrealized Losses - Amendments to IAS 12.

The amendments to IAS 7 require disclosure of changes in liabilities arising from financing activities, see note 3.3.

New standards, amendments and interpretations issued but not effective for the financial year beginning January 1, 2017 and not early adopted

A number of new standards and amendments to standards and interpretations have been issued but are not yet effective for annual periods beginning after January 1, 2017 (noted below), and have not been adopted in preparing these consolidated financial statements.


▪	IFRS 9 "Financial instruments" (effective for annual periods beginning on or after January 1, 2018)


▪	IFRS 15 "Revenue from contracts with customers" (effective for annual periods beginning on or after January 1, 2018


▪	IFRS 16 "Leases" (effective for annual periods beginning on or after January 1, 2019)

IFRS 9 will have no material impact on the accounting or measurement of any of the financial instruments the Company currently holds.

IFRS 15 will have no impact on the financial statements of the Company as it is not currently revenue generating.

IFRS 16 is effective for accounting periods beginning on or after 1 January 2019 and will replace IAS 17 'leases'. It will eliminate the classification of leases as either operating leases or finance leases and, instead, introduce a single lessee accounting model. The adoption of IFRS 16 will result in the Company recognizing lease liabilities and corresponding 'right to use' assets for agreements that are currently classified as operating leases. See note 20 for further details on operating leases held.

Financial Instruments

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about financial instruments [abstract]

Financial Instruments

Financial Risk Factors

The Company's activities have exposed it to a variety of financial risks: market risk (including currency risk and interest rate risk), credit risk, and liquidity risk. The Company's overall risk management program is focused on preservation of capital and the unpredictability of financial markets and has sought to minimize potential adverse effects on the Company's financial performance and position.

(a)Currency risk

Foreign currency risk reflects the risk that the Company's net assets will be negatively impacted due to fluctuations in exchange rates. The Company has not entered into foreign exchange contracts to hedge against gains or losses from foreign exchange fluctuations.

The summary quantitative date about the Company's exposure to currency risk is as follows. Figures are the sterling values of balances in each currency:



	Year Ended December 31, 2016		Year Ended December 31, 2017
	USD	EUR	USD	EUR
	£'000s	£'000s	£'000s	£'000s
Cash and cash equivalents	10,631	242	16,806	301
Short term Investments	—	—	19,718	—
Trade and other payables	305	180	276	403

Sensitivity Analysis

A reasonably possible strengthening (weakening) of the Euro, US dollar, or Sterling against all other currencies at 31 December would have affected the measurement of the financial instruments denominated in a foreign currency and affected equity and profit and loss by the amounts shown below. This analysis assumes that all other variables remain constant.



	Profit or loss and equity
	Strengthening	Weakening
December 31, 2017	£'000s	£'000s
EUR (5% movement)	35	(35	)
USD (5% Movement)	1,840	(1,840	)
December 31, 2016	£'000s	£'000s
EUR (5% movement)	21	(21	)
USD (5% Movement)	547	(547	)

Foreign currency denominated trade payables are short term in nature (generally 30 to 45 days). The Company has a U.S. operation, the net assets of which are exposed to foreign currency translation risk.

(b)Credit risk

Credit risk reflects the risk that the Company may be unable to recover contractual receivables. As the Company is still in the development stage no policies are currently required to mitigate this risk.

For banks and financial institutions, only independently rated parties with a minimum rating of "B+" are accepted. The Directors recognize that this is an area in which they may need to develop specific policies should the Company become exposed to further financial risks as the business develops.

As of December 31, 2017, and December 31, 2016, cash and cash equivalents and short term investments were placed at the following banks:



Cash and Cash Equivalents	Year ended December 31, 2016	Credit rating	Year ended December 31, 2017	Credit rating
	£'000		£'000
Banks
Royal Bank of Scotland	11,287	A3	16,623	A2
Lloyds Bank	28,447	A1	13,448	Aa3
Standard Chartered	—	—	1,242	A1
Wells Fargo	51	Aa1	130	Aa1
Total	39,785		31,443



Short Term Investments	Year ended December 31, 2016	Credit rating	Year ended December 31, 2017	Credit rating
	£'000		£'000
Banks
Royal Bank of Scotland	—	—	15,316	A2
Lloyds Bank	—	—	11,036	Aa3
Standard Chartered	—	—	22,467	A1
Wells Fargo	—	—	—	Aa1
Total	—		48,819

The Company considers capital to be its equity reserves. At the current stage of the Company's life cycle, the Company's objective in managing its capital is to ensure funds raised meet the research and operating requirements until the next development stage of the Company's suite of projects.

The Company ensures it is meeting its objectives by reviewing its Key Performance Indicators ("KPIs") to ensure the research activities are progressing in line with expectations, costs are controlled and unused funds are placed on deposit to conserve resources and increase returns on surplus cash held.

(d)Interest rate risk

As of December 31, 2017, the Company had cash deposits of £31.4 million (2016: £39.8 million) and short term investments of £48.8 million (2016: nil) . The rates of interest received during 2017 ranged between 0.0% and 1.73%. A 0.25% increase in interest rates would not have a material impact on finance income.The Company's exposure to interest rate risk, which is the risk that the interest received will fluctuate as a result of changes in market interest rates on classes of financial assets and financial liabilities, was as follows:



	December 31, 2016		December 31, 2017
	Floating interest rate	Fixed Interest rate	Floating interest rate	Fixed Interest rate
	£'000s	£'000s	£'000s	£'000s
Financial asset
Cash deposits	11,338	28,447	25,720	5,723
Short Term Investments	—	—	—	48,819
Total	11,338	28,447	25,720	54,542

(e)Liquidity risk

The Company prepares periodic working capital forecasts for the foreseeable future, allowing an assessment of the cash requirements of the Company, to manage liquidity risk. The following table provides an analysis of the Company's financial liabilities. The carrying value of all balances is equal to their fair value. The Company's maturity analysis for the derivative financial instrument from the issue of warrants is given in note 19.



	LESS THAN 1 YEAR	BETWEEN 1 AND 2 YEARS	BETWEEN 2 AND 5 YEARS	OVER 5 YEARS⁽¹⁾
	£'000s	£'000s	£'000s	£'000s
At December 31, 2016
Trade payables	719	—	—	—
Other payables	54	—	—	—
Accruals	2,050	—	—	—
Contingent obligation	—	—	—	1,807
Total	2,823	—	—	1,807


(1)	This table includes the undiscounted amount of the assumed contingent obligation. See note 18.



	LESS THAN 1 YEAR	BETWEEN 1 AND 2 YEARS	BETWEEN 2 AND 5 YEARS	OVER 5 YEARS⁽¹⁾
	£'000s	£'000s	£'000s	£'000s
At December 31, 2017
Trade payables	1,214	—	—	—
Other payables	74	—	—	—
Accruals	5,866	—	—	—
Contingent obligation	—	—	—	1,807
Total	7,154	—	—	1,807


(1)	This table includes the undiscounted amount of the assumed contingent obligation. See note 18.

Fair value estimation

The carrying amounts of cash and cash equivalents, receivables, accounts payable and accrued liabilities approximate to fair value due to their short-term nature. The carrying amount of the assumed contingent liability approximates to fair value as the underlying assumptions are currently similar.

For financial instruments that are measured in the Consolidated Statement of Financial Position at fair value, IFRS 7 requires disclosure of fair value measurements by level of the following fair value measurement hierarchy:


▪	Quoted prices (unadjusted) in active markets for identical assets or liabilities (level 1);


▪	Inputs other than quoted prices included within level 1 that are observable for the asset or liability, either directly or indirectly (level 2); and


▪	Inputs for the asset or liability that are not based on observable market data (level 3).

For the year ended December 31, 2017, and 2016, fair value adjustments to financial instruments through profit and loss resulted in the recognition of finance income of £6.7 million and £1.1 million respectively.

The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. These valuation techniques maximize the use of observable market data where it is available and rely as little as possible on entity specific estimates. If all significant inputs required to ascertain the fair value of an instrument are observable, the instrument is included in level 2. If one or more of the significant inputs are not based on observable market data, the instrument is included in level 3.



	Level 3	Total
	£'000s	£'000s
At December 31, 2017
Derivative financial instrument	1,273	1,273
Total	1,273	1,273

Movements in Level 3 items during the years ended December 31, 2016, and 2017 are as follows:



Derivative financial instrument	2016		2017
	£'000s		£'000s
At January 1	—		7,923
Initial recognition of derivative financial instrument	8,991		—
Fair value adjustments recognized in profit and loss	(1,068	)	(6,650	)
At December 31	7,923		1,273

Further details relating to the derivative financial instrument are set out in notes 4 and 19 of these financial statements.

In determining the fair value of the derivative financial instrument the Company applied the Black Scholes model; key inputs include the share price at reporting date, estimations on timelines, volatility and risk-free rates. These assumptions and the impact of changes in these assumptions, where material, are disclosed in note 19.

Change in liabilities arising from financing activities

The Company has provided a reconciliation so that changes in liabilities arising from financing activities, including both changes arising from cash flows and non-cash changes can be evaluated.



	December 31, 2017
	Derivative financial instrument
	£'000s
At January 1	7,923
Fair value adjustments - non cash	(6,650	)
At December 31	1,273

See note 19 for information relating to the derivative financial instrument.

Critical accounting estimates and judgments

12 Months Ended

Dec. 31, 2017

Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]

Critical accounting estimates and judgments

The preparation of financial statements in conformity with IFRS requires the use of accounting estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Although these estimates are based on management's best knowledge of current events and actions, actual results ultimately may differ from those estimates. IFRS also requires management to exercise its judgment in the process of applying the Company's accounting policies.

The areas involving a higher degree of judgment or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are as follows:

(a) Assumed contingent obligation

The Company has a material obligation for the future payment of royalties and milestones associated with contractual obligations on RPL554, a development product acquired as part of the acquisition of Rhinopharma The estimation of the fair value of the assumed contingent obligation on acquisition requires the selection of an appropriate valuation model, consideration as to the inputs necessary for the valuation model chosen, the estimation of the likelihood that the regulatory approval milestone will be achieved and estimates of the future cash flows and their timing (for further detail see note 19). The estimates for the assumed contingent obligation are based on a discounted cash flow model. Key assessments and judgments included in the fair value calculation of deferred consideration are:


▪	development, regulatory and marketing risks associated with progressing the product to market approval in key target territories;


▪	market size and product acceptance by clinicians, patients and reimbursement bodies;


▪	gross and net selling price;


▪	costs of manufacturing, product distribution and marketing support;


▪	launch of competitive products; and


▪	discount rate and time to crystallization of contingent consideration.

In accordance with IAS 39 ("Financial Instruments Recognition and Measurement" (para AG8)), when there is a change in the expected cash flows, the assumed contingent obligation is re-measured with the change in value going through the Consolidated Statement of Comprehensive Income. Cash flow estimates are revised when the probability of success changes. The assumed contingent obligation is measured at amortized cost with the discount unwinding in the Consolidated Statement of Comprehensive Income throughout the year. Actual outcomes could differ significantly from the estimates made.

The value of the assumed contingent obligation as of December 31, 2017 amounts to £0.9 million. (2016: £0.8 million). The increase in value of the assumed contingent obligation during 2017 amounted to £0.1 million (2016: £0.2 million) and the movement relates to unwinding the discount on the liability and retranslating for changes in US$ exchange rates. The increase was recorded in finance expense. There was no change in the year to the probability of success and consequently cash flow estimates were not revised.

The discount percentage applied is 12%.

(b) Valuation of the July 2016 warrants

Pursuant to the July 2016 Placement, the Company issued 31,115,926 units to new and existing investors at the placing price of £1.4365 per unit. Each unit comprises one ordinary share and one warrant. The warrants entitle the investors to subscribe for in aggregate a maximum of 12,446,370 ordinary shares.

In accordance with IAS 32 and Company accounting policy, as disclosed in note 2.15, the Company classified the warrants as a derivative financial liability to be presented on the Company's Consolidated Statement of Financial Position.

The fair value of these warrants is determined by applying the Black-Scholes model. Assumptions are made on inputs such as time to maturity, the share price, volatility and risk free rate in order to determine the fair value per warrant. For further details see note 19.

Transaction costs arising on the issues of these shares and warrants are allocated to the equity and warrant liability components in proportion to the allocation of proceeds.

The Company incurs research and development expenditure from third parties. The Company recognizes this expenditure in line with the management’s best estimation of the stage of completion of each research and development project. This includes the calculation of accrued costs at each period end to account for expenditure that has been incurred. This requires management to estimate full costs to complete for each project and also to estimate its current stage of completion. The costs related to the Clinical Research Organization expenses in the year was £18.5 million. The related accruals and prepayments were £4.6 million and £0.5 million respectively.

(d) Transaction costs related the Global Offering

The Company incurred various transaction costs relating to the Global Offering, including commissions, professional advisor fees, financial advice, listing fees and other costs. When management judged them to be incremental costs directly attributable to the transaction they were accounted for as a deduction from equity. Otherwise the costs were expensed to the consolidated income statement as incurred.

Operating loss

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Operating loss



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Operating Loss is stated after charging:
Research and development costs:
Employee benefits (note 8)	1,322	2,037	3,435
Amortization of patents (note 12)	43	51	111
Legal, professional consulting and listing fees	—	—	331
Loss on disposal of patents	136	—	—
Other research and development expenses	5,769	2,434	19,840
Total research and development costs	7,270	4,522	23,717
General and administrative costs:
Employee benefits (note 8)	625	865	2,857
Legal, professional consulting and listing fees	608	884	2,045
Amortization of computer software (note 12)	—	1	5
Loss on disposal of property, plant and equipment (note 13)	—	3	—
Depreciation of property, plant and equipment (note 13)	10	10	7
Operating lease charge — land and buildings	157	169	294
Loss on variations in foreign exchange rate	21	139	36
Other general and administrative expenses	285	427	795
Total general and administrative costs	1,706	2,498	6,039
Operating loss	8,976	7,020	29,756

Directors' emoluments and staff costs

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Directors' emoluments and staff costs



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
The average number of employees (excluding directors) of the Company during the year:
Research and Development	5	5	7
General and Administrative	3	2	5
Total	8	7	12



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Aggregate emoluments of directors:
Salaries and other short-term employee benefits	722	951	897
Social security costs	132	118	103
Incremental payment for additional services	89	44	—
Other pension costs	38	19	17
Total directors' emoluments	981	1,132	1,017
Share-based payment charge	232	257	1,037
Directors' emoluments including share-based payment charge	1,213	1,389	2,054



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Aggregate other staff costs:
Wages and salaries	540	1,027	2,136
Social security costs	42	98	182
Incremental payment for additional services	—	58	—
Share-based payment charge	137	319	1,882
Other pension costs	15	11	38
Total other staff costs	734	1,513	4,238

The Company operates a defined contribution pension scheme for U.K. employees and executive directors. The total pension cost during the year ended December 31, 2017 was £55 thousand (2016: £30 thousand and 2015: £53 thousand). There were no prepaid or accrued contributions to the scheme at December 31, 2017(2016 and 2015: £nil).

Finance income and expense

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Finance income and expense



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Finance income:
Interest received on cash balances	45	86	345
Foreign exchange gain on translating foreign currency denominated bank balances	—	687	—
Fair value adjustment on derivative financial instruments (note 19)	—	1,068	6,650
Other Income	—	—	23
Total finance income	45	1,841	7,018



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Finance expense:
Transaction costs allocated to the issue of warrants (note 19)	—	586	—
Foreign exchange loss on translating foreign currency denominated balances	—	—	2,392
Remeasurement of assumed contingent arrangement (note 18)	10	122	—
Unwinding of discount factor and foreign exchange movements related to the assumed contingent arrangement (note 18)	63	86	73
Total finance expense	73	794	2,465

Taxation

12 Months Ended

Dec. 31, 2017

Disclosure of income tax [Abstract]

Taxation



	Year ended December 31, 2015		Year ended December 31, 2016		Year ended December 31, 2017
	£'000s		£'000s		£'000s
Analysis of tax credit for the year
Current tax:
UK tax credit	(1,520	)	(1,067	)	(5,006	)
US tax charge	—		129		306
Adjustment in respect of prior periods	11		(16	)	(6	)
Total tax credit	(1,509	)	(954	)	(4,706	)
Factors affecting the tax charge for the year
Loss on ordinary activities	(9,002	)	(5,973	)	(25,203	)
Multiplied by standard rate of corporation tax of 19.25% (2016: 20% and 2015: 20.25%)	(1,823	)	(1,195	)	(4,852	)
Effects of:
Non-deductible expenses	114		292		675
Fair value adjustment on derivative financial instruments	—		(214	)	(1,280	)
Research and development incentive	(600	)	(427	)	(2,116	)
Temporary differences not recognized	(1	)	(4	)	(2	)
Difference in overseas tax rates	—		56		136
Tax losses carried forward not recognized	790		554		2,739
Adjustment in respect of prior periods	11		(16	)	(6	)
Total tax credit	(1,509	)	(954	)	(4,706	)

UK corporation tax is charged at 19.25% (2016: 20.00% and 2015: 20.25%) and U.S. federal tax at 35% (2016 and 2015: 35%).

The following tables represent deferred tax balances recognized in the Consolidated Statement of Financial Position. There were no movements in either the deferred tax asset or the deferred tax liability.



	Year ended December 31, 2016		Year ended December 31, 2017
	£'000s		£'000s
Deferred tax assets	250		250
Deferred tax liabilities	(250	)	(250	)
Net balances	—		—

The deferred tax liability relates to the difference between the accounting and tax bases of the IP R&D intangible asset. A deferred tax asset relating to UK tax losses has been recognized and offset against the liability.

Factors that may affect future tax charges

The Company has UK tax losses available for offset against future profits in the UK. However an additional deferred tax asset has not been recognized in respect of such items due to uncertainty of future profit streams. As of December 31, 2017, the unrecognized deferred tax asset at 17% is estimated to be £5.43 million (2016: £3.15 million at 17%).

Goodwill

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about intangible assets [abstract]

Goodwill



	As of December 31, 2016	As of December 31, 2017
	£'000s	£'000s
Goodwill at January 1 and December 31	441	441

Goodwill represents the excess of the purchase price over the fair value of the net assets acquired in connection with the acquisition of Rhinopharma in September 2006. Goodwill is not amortized, but is tested annually for impairment. Annual impairment testing is performed by comparing the expected recoverable amount of the CGU to the carrying amount of the CGU to which goodwill has been allocated to the carrying amount of the CGU. See note 2.8 to the consolidated financial statements.

Intangible assets

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about intangible assets [abstract]

Intangible assets



	IP R&D	Computer software		Patents	Total
	£'000s	£'000s		£'000s	£'000s
Cost
At January 1, 2016	1,469	25		482	1,976
Additions	—	5		110	115
Disposals	—	(24	)	—	(24	)
At December 31, 2016	1,469	6		592	2,067
Accumulated amortization
At January 1, 2016	—	24		138	162
Charge for year	—	1		51	52
Disposals	—	(24	)	—	(24	)
At December 31, 2016	—	1		189	190
Net book value
At December 31, 2016	1,469	5		403	1,877



	IP R&D	Computer software	Patents		Total
	£'000s	£'000s	£'000s		£'000s
Cost
At January 1, 2017	1,469	6	592		2,067
Additions	—	5	203		208
Disposals	—	—	(68	)	(68	)
At December 31, 2017	1,469	11	727		2,207
Accumulated amortization
At January 1, 2017	—	1	189		190
Charge for year	—	5	111		116
Disposals	—	—	(68	)	(68	)
At December 31, 2017	—	6	232		238
Net book value
At December 31, 2017	1,469	5	495		1,969

Intangible assets comprise patents, computer software and an IP R&D asset that arose on the acquisition of Rhinopharma and investment in patents to protect RPL554.

IP R&D is currently not amortized and is reviewed for impairment on an annual basis or where there is an indication that the assets might be impaired until the asset is brought into use.

Patents are amortized over a period of ten years and are regularly reviewed for impairment to ensure the carrying amount exceeds the recoverable amount in accordance with note 2.8.

Recognizing that the Company is still in its pre-revenue phase and that the research projects are not yet ready for commercial use, the Company assesses the recoverable amount of the CGU containing the IP R&D with reference to the Company's market capitalization as of December 31, 2017, the date of testing of goodwill impairment. The market capitalization of the Company was approximately £109.7 million as of December 31, 2017, (2016: £80.0 million) compared to the Company's net assets of £79.9 million (2016: £34.5 million). Therefore, no impairment was recognized.

Property, plant and equipment

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about property, plant and equipment [abstract]

Property, plant and equipment



	Computer hardware		Office equipment		Total
	£'000s		£'000s		£'000s
Cost
At January 1, 2016	43		36		79
Additions	13		—		13
Disposals	(39	)	(36	)	(75	)
At December 31, 2016	17		—		17
Accumulated depreciation
At January 1, 2016	39		27		66
Charge for the year	3		7		10
Disposals	(39	)	(34	)	(73	)
At December 31, 2016	3		—		3
Net book value
At December 31, 2016	14		—		14



	Computer hardware	Office equipment	Total
	£'000s	£'000s	£'000s
Cost
At January 1, 2017	17	—	17
Additions	9	—	9
At December 31, 2017	26	—	26
Accumulated depreciation
At January 1, 2017	3	—	3
Charge for the year	7	—	7
At December 31, 2017	10	—	10
Net book value
At December 31, 2017	16	—	16

Prepayments and other receivables

12 Months Ended

Dec. 31, 2017

Subclassifications of assets, liabilities and equities [abstract]

Prepayments and other receivables



	As of December 31, 2016	As of December 31, 2017
	£'000s	£'000s
Prepayments	1,361	1,138
Deferred IPO costs	1,527	—
Other receivables	71	672
Total prepayments and other receivables	2,959	1,810

Deferred IPO costs related to the Global Offering. These costs were offset against share premium in 2017 when the Global Offering was completed.

The prepayments balance includes prepayments for insurance and clinical activities.

There are no impaired assets within prepayments and other receivables.

Share Capital

12 Months Ended

Dec. 31, 2017

Disclosure of share capital, reserves and other equity interest [Abstract]

Share Capital

On February 8, 2017, the board of the Company approved a share consolidation where every 50 existing ordinary shares of £0.001 were consolidated into one ordinary share of £0.05. The movements in the Company's share capital are summarized below:



Date	Description	Number of shares	Share Capital amounts in
Date	Description	Number of shares	£'000
January 1, 2016		20,198,469	1,010
July 29, 2016	Issuance of shares	31,115,926	1,556
September 12, 2016	Exercise of options	3,334	—
October 24, 2016	Exercise of options	3,334	—
December 28, 2016	Exercise of options	40,000	2
As at December 31, 2016		51,361,063	2,568
May 2, 2017	Issuance of shares	47,653,100	2,383
May 18, 2017	Issuance of shares	5,539,080	277
May 26, 2017	Issuance of shares	330,824	17
September 13, 2017	Exercise of options	133,333	6
December 31, 2017		105,017,400	5,251

The total number of authorized ordinary shares, with a nominal value of £0.05 each, is 200,000,000 (share capital of £10,000,000). All 105,017,400 ordinary shares at December 31, 2017 are allotted, unrestricted, called up and fully paid.

On April 26, 2017, the Company announced the closing of its Global Offering of an aggregate of 47,399,001 new ordinary shares, comprising 5,768,000 American Depositary Shares (“ADSs”) at a price of $13.50 per ADS and 1,255,001 ordinary shares at a price of £1.32 per ordinary share. During May 2017 the underwriters purchased an additional 733,738 ADSs, representing 5,869,904 ordinary shares, at a price of $13.50 per ADS. The total gross proceeds in the Global Offering amounted to $89.9 million (£70.0 million).

In addition, the Chairman of Verona Pharma’s board of directors, Dr David Ebsworth, and an existing shareholder agreed to subscribe for 254,099 new ordinary shares at a price of £1.32 per ordinary share in the Shareholder Private Placement, contingent on and concurrent with the Global Offering and generating gross proceeds of £0.3m.

Where there is a time and foreign exchange difference between proceeds from a share issue becoming due and being received, the movement is taken to Finance income or Finance expense as appropriate. In respect of the Global Offering and Shareholder Private Placement, the Company recorded a finance expense of £439 thousand arising from movements in exchange rates on funds receivable, offset by a saving on commission payable of £31 thousand, for a net finance expense of £408 thousand.

On September 13, 2017, the company issued 133,333 new shares upon exercise of share options at 110p per share, resulting in proceeds of £147 thousand to the Company.

On July 29, 2016, the Company issued 31,115,926 units to new and existing investors at the placing price of £1.4365 per unit. Each unit comprises one ordinary share and one warrant (see note 19).

During 2016, the Company issued 46,666 ordinary shares upon exercise of employee share options.

As at December 31, 2017, the number of ordinary shares in issue was 105,017,400. All new ordinary shares rank pari passu with existing ordinary shares.

Share-based payments charge

12 Months Ended

Dec. 31, 2017

Disclosure of share-based payment arrangements [Abstract]

Share-based payments charge

In accordance with IFRS 2 "Share Based Payments," the cost of equity-settled transactions is measured by reference to their fair value at the date at which they are granted. Where equity-settled transactions were entered into with third party service providers, fair value is determined by reference to the value of the services provided. For other equity-settled transactions fair value is determined using the Black-Scholes model. The cost of equity-settled transactions is recognized over the period until the award vests. No expense is recognized for awards that do not ultimately vest. At each reporting date, the cumulative expense recognized for equity-based transactions reflects the extent to which the vesting period has expired and the number of awards that, in the opinion of the Directors at that date, will ultimately vest.

The costs of equity-settled share-based payments to employees are recognized in the Statement of Comprehensive Income, together with a corresponding increase in equity during the vesting period. During the twelve months ended December 31, 2017, the Company recognized a share-based payment expense of £2.92 million (2016: £0.58 million ). The charge is included within both general and administrative costs as well as in research and development costs and represents the current year's allocation of the expense for relevant share options.

The Company grants share options under an Unapproved Share Option Scheme (the "Unapproved Scheme"). Under the Unapproved Scheme, options are granted to employees, directors and consultants to acquire shares at a price to be determined by the Directors. In general, options granted prior to December 31, 2016 were granted at a premium to the share price at the date of grant and vested over a period of three years from the date of grant, one third vesting on the first anniversary of grant, a further third vesting on the second anniversary of grant and the remainder vesting on the third anniversary of grant.

Options granted since January 1, 2017 generally vest over three or four years from the date of the grant using two different methods. The first method is one third vesting over one year, the second third vesting over two years and the final third vesting over three years. The second method is one quarter vesting over one year, the second quarter vesting over two years, the third quarter vesting over three years and the final quarter vesting over four years. The vesting period is defined as the period between the date of grant and the date when the options become exercisable. The options are exercisable during a period ending ten years after the date of grant.

Options are also issued to advisors under the Unapproved Scheme. Such options generally vest immediately and are exercisable between one and two years after grant.

In 2016 the Company issued options under its tax efficient EMI Option Scheme (the "EMI Scheme"). Under the EMI Scheme, options were granted to employees and directors who are contracted to work at least 25 hours a week for the Company or for at least 75% of their working time. The options granted under the EMI Scheme are exercisable at a price that is above the share price at the date of the grant and in accordance with a vesting schedule determined by the Directors at the time of grant and have an exercise period of ten years from the date of grant.

The Company grants Restricted Stock Units to employees and directors. The RSUs vest over a period of three or four years from the date of the grant using 2 different methods. The first method is one third vesting over one year, the second third vesting over two years and the final third vesting over three years. The second method is one quarter vesting over one year, the second quarter vesting over two years, the third quarter vesting over three years and the final quarter vesting over four years.

In the year ended December 31, 2017, the Company granted 4,656,828 (2016: 1,670,000 ) share options, nil (2016: 32,000) share options under the EMI Scheme and 1,052,236 Restricted Stock Units (“RSUs”) (2016: nil). The total fair values of the Options and RSUs were estimated using the Black-Scholes option-pricing model for equity-settled transactions and amounted to £5.33 million (2016: £1.93 million). The cost is amortized over the vesting period of the options on a straight-line basis.

Prior to the July 2016 Placement in 2016, management determined to take an option's contractual maximum life as an input into the Black-Scholes option-pricing model. Starting from the July 2016 Placement and in line with the continued development of the Company's clinical trials, the Company determined the time to maturity to be used in the valuation model to be better represented by the weighted-average life of the options granted.

The following assumptions were used for the Black-Scholes valuation of share options granted in 2016 and 2017. For the options granted under the Unapproved Scheme the table indicates the ranges used in determining the fair-market values, aligning with the various dates of the underlying grants. The volatility is calculated using historic weekly averages of the Company's share price over a period that is in line with the expected life of the options.



Issued in 2016	EMI Scheme		Unapproved Scheme
Options granted	32,000		1,670,000
Risk-free interest rate	1.42	%	0.23%-1.42%
Expected life of options	10 years		5.5-10 years
Annualized volatility	88.0	%	74.3% - 88.0%
Dividend rate	0.00	%	0.00	%
Vesting period	3 years		3 years

Issued in 2017	Unapproved Scheme		Restricted Stock Units
Options granted	4,656,828		1,052,236
Risk-free interest rate	0.29% - 0.62%		0.42%-0.62%
Expected life of options	5.5 – 7.0 years		5.5 – 7.0 years
Annualized volatility	71.3% - 73.3%		71.3% - 73.3%
Dividend rate	0.00	%	0.00	%
Vesting period	3 and 4 years		3 and 4 years

The Company had the following share options movements in the year ended December 31, 2017:



Year of issue	Exercise price (£)	At January 1, 2017	Options granted	Options exercised		Options forfeited	Options expired		At December 31, 2017	Expiry date
2012	2.50 - 7.50	100,000	—	—		—	—		100,000	June 1, 2022
2013	2	100,000	—	—		—	—		100,000	April 15, 2023
2013	2.00	20,000	—	—		—	(20,000	)	—	June 1, 2023	*
2013	2.00	160,000	—	—		—	—		160,000	July 29, 2023
2014	1.75	110,000	—	—		—	—		110,000	May 15, 2024
2014	1.75	63,333	—	—		—	(13,333	)	50,000	May 15, 2024	*
2014	1.10 - 1.75	200,000	—	(133,333	)	—	—		66,667	August 6, 2018	**
2015	1.25	82,000	—	—		—	—		82,000	January 29, 2025	*
2015	1.25	510,000	—	—		—	—		510,000	January 29, 2025
2016	2	260,000	—	—		—	—		260,000	February 2, 2026
2016	2.00	22,000	—	—		—	—		22,000	February 2, 2026	*
2016	1.80	810,000	—	—		—	—		810,000	August 3, 2026
2016	1.89	300,000	—	—		—	—		300,000	September 13, 2026
2016	2.04	300,000	—	—		—	—		300,000	September 16, 2026
2017	1.32 - 1.525	—	4,656,828	—		—	—		4,656,828	April 26, 2027
Total		3,037,333	4,656,828	(133,333	)	—	(33,333	)	7,527,495


*	Options granted under the EMI Scheme.

* * Valued based on fair value of services received.

The Company had the following Restricted Share Units movements in the year ended December 31, 2017:



Year of issue	Exercise price (£)	At January 1, 2017		Units granted		Units exercised		Units forfeited		Units expired		At December 31, 2017	Expiry date
2017		—		1,052,236		—		—		—		1,052,236	April 26, 2027
Total		—	—	1,052,236	—	—	—	—	—	—	—	1,052,236

The average fair value at grant date, by year of grant and plan, of the exercisable options as per December 31, 2017 is presented in the below table.



Year of issue	EMI Scheme (£)	Unapproved Scheme (£)	RSU (£)
2012	0.63 - 1.20	—	—
2013	0.83	0.79 - 0.95
2014	0.76	0.23 - 0.76
2015	0.57	0.57
2016	1.35	0.93 - 1.35
2017	—	0.84	1.33

Outstanding and exercisable share options by scheme as of December 31, 2017:



Plan	Outstanding	Exercisable	Weighted average exercise price in £ for Outstanding	Weighted average exercise price in £ for Exercisable
Unapproved	7,313,473	773,333	1.50	1.64
EMI	213,984	185,333	3.06	3.28
Total	7,527,457	958,666	1.54	1.95

As at December 31, 2017 there were no restricted share options exercisable (2016: nil) and there is no exercise price for restricted share options.

The options outstanding at December 31, 2017 had a weighted average remaining contractual life of 8.6 years (2016: 8.2 years). For 2016 and 2017, the number of options granted and expired and the weighted average exercise price of options were as follows:



	Number of options		Weighted average exercise price (£)
At January 1, 2016	1,792,000		1.78
Options granted in 2016:
Employees	1,002,000		1.92
Directors	700,000		2.05
Options exercised in the year	(46,666	)	1.12
Options forfeited in the year	(150,001	)	1.24
Options expired in the year	(260,000	)	2.46
At December 31, 2016	3,037,333		1.87
Exercisable at December 31, 2016	846,667		2.25



	Number of options		Weighted average exercise price (£)
At January 1, 2017	3,037,333		1.87
Options granted in 2017:
Employees	3,150,846		1.32
Directors	1,505,982		1.32
Options exercised in the year	(133,333	)	1.10
Options forfeited in the year	—		—
Options expired in the year	(33,333	)	1.90
At December 31, 2017	7,527,495		1.53
Exercisable at December 31, 2017	797,333		2.04

The following table shows the number of RSUs issued in 2017. No RSUs were granted in 2016 and none of the RSUs granted in 2017 were forfeited, canceled or vested in the year. The fair value of each unvested RSU at grant date was £1.32.



		Number of RSUs
At January 1, 2017		—
Granted:
Employees		705,841
Directors		346,395
At December 31, 2017		1,052,236

Assumed contingent obligation related to the business combination

12 Months Ended

Dec. 31, 2017

Disclosure of other provisions, contingent liabilities and contingent assets [Abstract]

Assumed contingent obligation related to the business combination

The value of the assumed contingent obligation as of December 31, 2017 amounts to £875 thousand (2016: £802 thousand). The increase in value of the assumed contingent obligation during 2017 amounted to £73 thousand (2016: £208 thousand ) and was recorded in finance expense as it related to the unwind of the discount on the liability and retranslation for changes in US$ exchange rates. Periodic re-measurement is triggered by changes in the probability of success. In 2016 the remeasurement was triggered by the success of the Company's Phase 2a clinical trial, presented in March 2016. The discount percentage applied is 12%. In 2017 there were no events that triggered remeasurement.



	2016	2017
	£'000s	£'000s
January 1	594	802
Re-measurement of assumed contingent obligation	86	—
Impact of changes in foreign exchange rates	37	(23	)
Unwinding of discount factor	85	96
December 31	802	875

The table below describes the reported change to the value of the liability during 2017 of £73 thousand (2016: £208 thousand) compared to what this number would be following the presented variations to the underlying assumptions (assuming the probability of success does not change):



	2016	2017
	£'000s	£'000s
Change in value of the assumed contingent obligation	208	73
10% lower revenue assumption	202	72
10% higher revenue assumption	215	73
1% lower risk assumption	205	69
1% higher risk assumption	211	76

Warrants

12 Months Ended

Dec. 31, 2017

Disclosure of share capital, reserves and other equity interest [Abstract]

Warrants

Pursuant to the July 2016 Placement, on July 29, 2016 the Company issued 31,115,926 units to new and existing investors at the placing price of £1.4365 per unit. Each unit comprises one ordinary share and one warrant.

The warrant holders can subscribe for 0.4 of an ordinary share at a per share exercise price of 120% of the placing price or £1.7238. The warrant holders can opt for a cashless exercise of their warrants, whereby the warrant holders can choose to exchange the warrants held for reduced number of warrants exercisable at nil consideration. The reduced number of warrants is calculated based on a formula considering the share price and the exercise price of the warrants. The warrants are therefore classified as a derivative financial liability, since their exercise could result in a variable number of shares to be issued.

The warrants entitled the investors to subscribe for in aggregate a maximum of 12,446,370 shares. The warrants can be exercised on the earlier of the consummation of the Global Offering (being April 26, 2017) or the first anniversary of the grant, and the exercise period shall end on the fifth anniversary of the date of grant (being July 29, 2021).

The ordinary shares and warrants were accounted for as a compound financial instrument. The warrants component of the instrument issued at the July 2016 Placement was classified as a derivative financial liability and was initially measured at fair value of £9.0 million. The residual amount of proceeds totaling £35.7 million was recognized within equity. Subsequently the financial liability was re-measured at the reporting date at fair value through profit or loss.

The total of transaction costs the Company incurred for the above transactions amounted to £2.9 million of which £0.6 million was allocated to the warrants and the remaining £2.3 million was presented as a reduction to share premium, by reference to the proceeds allocated to each component. The amount assigned to the financial liability of the warrants was subsequently presented as finance expense in the Consolidated Statement of Comprehensive Income.

In the year ended 31 December 2017 warrants over 45,108 shares were forfeited (2016: nil).

The table below presents the assumptions in applying the Black-Scholes model to determine the fair value of the warrants.



	As of December 31, 2016			As of December 31, 2017
Shares available to be issued under warrants	12,446,370			12,401,262
Exercise price	£	1.7238		£	1.7238
Risk-free interest rate	0.088		%	0.420		%
Expected term to exercise	2.43 years			1.79 years
Annualized volatility	73.53		%	47.35		%
Dividend rate	0.00		%	0.00		%

The figures disclosed above relating to the issue of the shares and warrants have been retrospectively adjusted to reflect the 50-for-1 share consolidation as described in note 1. The original number of units issued to new and existing investors was 1,555,796,345 units at a placing price of 2.873 pence per unit and an exercise price of 3.4476 pence per share. This entitled the investors to subscribe for in aggregate a maximum of 622,318,538 shares.

As per the reporting date the Company updated the underlying assumptions and calculated a fair value of these warrants amounting to £1.3 million. The variance of £6.7 million is recorded as finance income in the Consolidated Statement of Comprehensive Income.



	Derivative financial instrument		Derivative financial instrument
	2016		2017
	£'000s		£'000s
At January 1	—		7,923
On issuance of shares	8,991		—
Fair value adjustments recognized in profit or loss	(1,068	)	(6,650	)
At December 31	7,923		1,273

For the amount recognized at December 31, 2017, the effect when some of these underlying parameters would deviate up or down is presented in the below table.



	Volatility (up / down 10% pts)	Time to maturity (up / down 6 months)
	£'000s	£'000s
Variable up	1,921	1,677
Base case, reported fair value	1,273	1,273
Variable down	694	843

Financial commitments

12 Months Ended

Dec. 31, 2017

Disclosure of leases [Abstract]

Financial commitments

As of December 31, 2017, the Company was committed to making the following payments under non-cancellable operating leases related to its facilities.



	Land and Buildings	Land and Buildings
	2016	2017
	£'000s	£'000s
Operating lease obligations:
Within one year	270	291
Between one and five years	—	277
Total	270	568

Related parties transactions and other shareholder matters	12 Months Ended
	Dec. 31, 2017
Disclosure of related party [Abstract]
Related parties transactions and other shareholder matters	Related parties transactions and other shareholder matters (i) Related party transactions The Directors have authority and responsibility for planning, directing and controlling the activities of the Company and they therefore comprise key management personnel as defined by IAS 24, ("Related Party Disclosures"). (ii) Other shareholder matters The Company has entered into the following arrangements with parties who are significant shareholders of the Company, though they are not classed as related parties. The Company entered into relationship agreements with Vivo Capital Fund VIII ("Vivo Capital"), Orbimed Private Investments VI L.P. ("Orbimed"), Abingworth Bioventures VI L.P. ("Abingworth"), and Arix Bioscience plc ("Arix") and Arthurian Life Sciences SPV GP Limited, ("Arthurian"). As agreed in these relationship agreements, the above parties invested in the Company as part of the July 2016 Placement, and the Company agreed to appoint representatives designated by Vivo Capital, OrbiMed, Abingworth, and Arix and Arthurian, to the board of directors, who are Dr. Mahendra Shah, Mr. Rishi Gupta, Dr. Andrew Sinclair and Dr. Ken Cunningham respectively. The appointment rights within the relationship agreement with Arix and Arthurian terminated on closing of the Global Offering on April 26, 2017; Dr Cunningham has agreed to continue to serve on the Company's board of directors as an independent director. The respective appointment rights under the remaining relationship agreements will automatically terminate upon (i) Vivo Capital, OrbiMed or Abingworth (or any of their associates), as applicable, ceasing to beneficially hold 6.5% of the issued ordinary shares, or (ii) the ordinary shares ceasing to be admitted to AIM. The Company also entered into a management rights agreement with Novo A/S under which Novo A/S was entitled to appoint an observer to the Board; the appointment rights within the management rights agreement terminated on closing of the Global Offering on April 26, 2017.

Accounting policies (Policies)

12 Months Ended

Dec. 31, 2017

Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]

Going concern

Business combination

Basis of consolidation

Inter-company transactions, balances and unrealized gains on transactions between group companies are eliminated.

Verona Pharma Inc. and Rhinopharma adopt the same accounting policies as the Company.

Foreign currency translation

Cash and cash equivalents

Cash and cash equivalents includes cash in hand, deposits held at call with banks and other short-term highly liquid investments with original maturities of three months or less.

Deferred taxation

Deferred tax assets are recognized to the extent that it is probable that the future taxable profit will be available against which the temporary differences can be utilized.

Research and development costs

Expenditure on research and development activities that do not meet the above criteria is charged to the Consolidated Statement of Comprehensive Income as incurred.

Property, plant and equipment

Intangible assets and goodwill


(a)	Goodwill

Goodwill arises on the acquisition of subsidiaries and represents the excess of the consideration transferred over the fair value of the identifiable net assets acquired.


(b)	Patents

Patent costs associated with the preparation, filing, and obtaining of patents are capitalized and amortized on a straight-line basis over the estimated useful lives of the patents of ten years.


(c)	Computer software

Amortization is calculated so as to write off the cost less estimated residual values, on a straight-line basis over the expected useful economic life of two years.


(d)	In-process research & development ("IPR&D")

Impairment of intangible assets, goodwill and non-financial asset

Impairment of intangible assets, goodwill and non-financial assets

Non-financial assets, other than goodwill, that have been previously impaired are reviewed for possible reversal of the impairment at each subsequent reporting date.

Employee Benefits


(a)	Pension


(b)	Bonus plans

The Company recognizes a liability and an expense for bonus plans if contractually obligated or if there is a past practice that has created a constructive obligation.

Share-based payments

Provisions

Assumed contingent obligation related to the business combinations

Government and other grants

Financial instruments — initial recognition and subsequent measurement

A financial instrument is any contract that gives rise to a financial asset of one entity and a financial liability or equity instrument of another entity.


(a)	Financial assets, initial recognition and measurement and subsequent measurement


(b)	Financial liabilities, initial recognition and measurement and subsequent measurement

The Company's financial liabilities include trade and other payables and derivative financial instruments.

Warrants

Warrants issued by the Company to investors as part of a share subscription are compound financial instruments where the warrant meets the definition of a financial liability.

Short Term Investments

Transaction costs

Investments in subsidiaries

Investments in subsidiaries are shown at cost less any provision for impairment.

New standards, amendments and interpretations adopted by the Group

New standards, amendments and interpretations adopted by the Company

The following amendments have been adopted by the Company for the first time for the financial year beginning on or after 1 January, 2017. It did not materially impact the Company’s results:

· Annual Improvements to IFRS Standards 2014-2016 Cycle,

· Disclosure initiative - amendments to IAS 7, and

· Recognition of Deferred Tax Assets for Unrealized Losses - Amendments to IAS 12.

The amendments to IAS 7 require disclosure of changes in liabilities arising from financing activities, see note 3.3.

New standards, amendments and interpretations issued but not effective for the financial year beginning January 1, 2016 and not early adopted

New standards, amendments and interpretations issued but not effective for the financial year beginning January 1, 2017 and not early adopted


▪	IFRS 9 "Financial instruments" (effective for annual periods beginning on or after January 1, 2018)


▪	IFRS 15 "Revenue from contracts with customers" (effective for annual periods beginning on or after January 1, 2018


▪	IFRS 16 "Leases" (effective for annual periods beginning on or after January 1, 2019)

IFRS 9 will have no material impact on the accounting or measurement of any of the financial instruments the Company currently holds.

IFRS 15 will have no impact on the financial statements of the Company as it is not currently revenue generating.

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about financial instruments [abstract]

Summary quantitative data about entity's exposure to risk

The summary quantitative date about the Company's exposure to currency risk is as follows. Figures are the sterling values of balances in each currency:



	Year Ended December 31, 2016		Year Ended December 31, 2017
	USD	EUR	USD	EUR
	£'000s	£'000s	£'000s	£'000s
Cash and cash equivalents	10,631	242	16,806	301
Short term Investments	—	—	19,718	—
Trade and other payables	305	180	276	403

Disclosure of effect of changes in foreign exchange rates



	Profit or loss and equity
	Strengthening	Weakening
December 31, 2017	£'000s	£'000s
EUR (5% movement)	35	(35	)
USD (5% Movement)	1,840	(1,840	)
December 31, 2016	£'000s	£'000s
EUR (5% movement)	21	(21	)
USD (5% Movement)	547	(547	)

Disclosure of cash and cash equivalents and short term investments

As of December 31, 2017, and December 31, 2016, cash and cash equivalents and short term investments were placed at the following banks:



Cash and Cash Equivalents	Year ended December 31, 2016	Credit rating	Year ended December 31, 2017	Credit rating
	£'000		£'000
Banks
Royal Bank of Scotland	11,287	A3	16,623	A2
Lloyds Bank	28,447	A1	13,448	Aa3
Standard Chartered	—	—	1,242	A1
Wells Fargo	51	Aa1	130	Aa1
Total	39,785		31,443



Short Term Investments	Year ended December 31, 2016	Credit rating	Year ended December 31, 2017	Credit rating
	£'000		£'000
Banks
Royal Bank of Scotland	—	—	15,316	A2
Lloyds Bank	—	—	11,036	Aa3
Standard Chartered	—	—	22,467	A1
Wells Fargo	—	—	—	Aa1
Total	—		48,819

Disclosure of financial instruments by type of interest rate

The Company's exposure to interest rate risk, which is the risk that the interest received will fluctuate as a result of changes in market interest rates on classes of financial assets and financial liabilities, was as follows:



	December 31, 2016		December 31, 2017
	Floating interest rate	Fixed Interest rate	Floating interest rate	Fixed Interest rate
	£'000s	£'000s	£'000s	£'000s
Financial asset
Cash deposits	11,338	28,447	25,720	5,723
Short Term Investments	—	—	—	48,819
Total	11,338	28,447	25,720	54,542

Disclosure of maturity analysis of undiscounted cash outflows to repurchase derecognised financial assets or amounts payable to transferee in respect of transferred assets

The following table provides an analysis of the Company's financial liabilities. The carrying value of all balances is equal to their fair value. The Company's maturity analysis for the derivative financial instrument from the issue of warrants is given in note 19.



	LESS THAN 1 YEAR	BETWEEN 1 AND 2 YEARS	BETWEEN 2 AND 5 YEARS	OVER 5 YEARS⁽¹⁾
	£'000s	£'000s	£'000s	£'000s
At December 31, 2016
Trade payables	719	—	—	—
Other payables	54	—	—	—
Accruals	2,050	—	—	—
Contingent obligation	—	—	—	1,807
Total	2,823	—	—	1,807


(1)	This table includes the undiscounted amount of the assumed contingent obligation. See note 18.



	LESS THAN 1 YEAR	BETWEEN 1 AND 2 YEARS	BETWEEN 2 AND 5 YEARS	OVER 5 YEARS⁽¹⁾
	£'000s	£'000s	£'000s	£'000s
At December 31, 2017
Trade payables	1,214	—	—	—
Other payables	74	—	—	—
Accruals	5,866	—	—	—
Contingent obligation	—	—	—	1,807
Total	7,154	—	—	1,807


(1)	This table includes the undiscounted amount of the assumed contingent obligation. See note 18.

Disclosure of fair value measurement of assets



	Level 3	Total
	£'000s	£'000s
At December 31, 2017
Derivative financial instrument	1,273	1,273
Total	1,273	1,273

Disclosure of fair value measurement of liabilities



	Level 3	Total
	£'000s	£'000s
At December 31, 2017
Derivative financial instrument	1,273	1,273
Total	1,273	1,273



	December 31, 2017
	Derivative financial instrument
	£'000s
At January 1	7,923
Fair value adjustments - non cash	(6,650	)
At December 31	1,273

Disclosure of significant unobservable inputs used in fair value measurement of liabilities

Movements in Level 3 items during the years ended December 31, 2016, and 2017 are as follows:



Derivative financial instrument	2016		2017
	£'000s		£'000s
At January 1	—		7,923
Initial recognition of derivative financial instrument	8,991		—
Fair value adjustments recognized in profit and loss	(1,068	)	(6,650	)
At December 31	7,923		1,273

Operating loss (Tables)

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Description of operating loss



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Operating Loss is stated after charging:
Research and development costs:
Employee benefits (note 8)	1,322	2,037	3,435
Amortization of patents (note 12)	43	51	111
Legal, professional consulting and listing fees	—	—	331
Loss on disposal of patents	136	—	—
Other research and development expenses	5,769	2,434	19,840
Total research and development costs	7,270	4,522	23,717
General and administrative costs:
Employee benefits (note 8)	625	865	2,857
Legal, professional consulting and listing fees	608	884	2,045
Amortization of computer software (note 12)	—	1	5
Loss on disposal of property, plant and equipment (note 13)	—	3	—
Depreciation of property, plant and equipment (note 13)	10	10	7
Operating lease charge — land and buildings	157	169	294
Loss on variations in foreign exchange rate	21	139	36
Other general and administrative expenses	285	427	795
Total general and administrative costs	1,706	2,498	6,039
Operating loss	8,976	7,020	29,756

Directors' emoluments and staff costs (Tables)

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Disclosure of information about employees



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
The average number of employees (excluding directors) of the Company during the year:
Research and Development	5	5	7
General and Administrative	3	2	5
Total	8	7	12



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Aggregate emoluments of directors:
Salaries and other short-term employee benefits	722	951	897
Social security costs	132	118	103
Incremental payment for additional services	89	44	—
Other pension costs	38	19	17
Total directors' emoluments	981	1,132	1,017
Share-based payment charge	232	257	1,037
Directors' emoluments including share-based payment charge	1,213	1,389	2,054



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Aggregate other staff costs:
Wages and salaries	540	1,027	2,136
Social security costs	42	98	182
Incremental payment for additional services	—	58	—
Share-based payment charge	137	319	1,882
Other pension costs	15	11	38
Total other staff costs	734	1,513	4,238

Finance income and expense (Tables)

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Disclosure of finance income



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Finance income:
Interest received on cash balances	45	86	345
Foreign exchange gain on translating foreign currency denominated bank balances	—	687	—
Fair value adjustment on derivative financial instruments (note 19)	—	1,068	6,650
Other Income	—	—	23
Total finance income	45	1,841	7,018

Disclosure of finance expense



	Year ended December 31, 2015	Year ended December 31, 2016	Year ended December 31, 2017
	£'000s	£'000s	£'000s
Finance expense:
Transaction costs allocated to the issue of warrants (note 19)	—	586	—
Foreign exchange loss on translating foreign currency denominated balances	—	—	2,392
Remeasurement of assumed contingent arrangement (note 18)	10	122	—
Unwinding of discount factor and foreign exchange movements related to the assumed contingent arrangement (note 18)	63	86	73
Total finance expense	73	794	2,465

Taxation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of income tax [Abstract]

Disclosure of major tax components



	Year ended December 31, 2015		Year ended December 31, 2016		Year ended December 31, 2017
	£'000s		£'000s		£'000s
Analysis of tax credit for the year
Current tax:
UK tax credit	(1,520	)	(1,067	)	(5,006	)
US tax charge	—		129		306
Adjustment in respect of prior periods	11		(16	)	(6	)
Total tax credit	(1,509	)	(954	)	(4,706	)
Factors affecting the tax charge for the year
Loss on ordinary activities	(9,002	)	(5,973	)	(25,203	)
Multiplied by standard rate of corporation tax of 19.25% (2016: 20% and 2015: 20.25%)	(1,823	)	(1,195	)	(4,852	)
Effects of:
Non-deductible expenses	114		292		675
Fair value adjustment on derivative financial instruments	—		(214	)	(1,280	)
Research and development incentive	(600	)	(427	)	(2,116	)
Temporary differences not recognized	(1	)	(4	)	(2	)
Difference in overseas tax rates	—		56		136
Tax losses carried forward not recognized	790		554		2,739
Adjustment in respect of prior periods	11		(16	)	(6	)
Total tax credit	(1,509	)	(954	)	(4,706	)

Disclosure of temporary difference, unused tax losses and unused tax credits



	Year ended December 31, 2016		Year ended December 31, 2017
	£'000s		£'000s
Deferred tax assets	250		250
Deferred tax liabilities	(250	)	(250	)
Net balances	—		—

Intangible assets (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about intangible assets [abstract]

Disclosure of reconciliation of changes in intangible assets and goodwill



	IP R&D	Computer software		Patents	Total
	£'000s	£'000s		£'000s	£'000s
Cost
At January 1, 2016	1,469	25		482	1,976
Additions	—	5		110	115
Disposals	—	(24	)	—	(24	)
At December 31, 2016	1,469	6		592	2,067
Accumulated amortization
At January 1, 2016	—	24		138	162
Charge for year	—	1		51	52
Disposals	—	(24	)	—	(24	)
At December 31, 2016	—	1		189	190
Net book value
At December 31, 2016	1,469	5		403	1,877



	IP R&D	Computer software	Patents		Total
	£'000s	£'000s	£'000s		£'000s
Cost
At January 1, 2017	1,469	6	592		2,067
Additions	—	5	203		208
Disposals	—	—	(68	)	(68	)
At December 31, 2017	1,469	11	727		2,207
Accumulated amortization
At January 1, 2017	—	1	189		190
Charge for year	—	5	111		116
Disposals	—	—	(68	)	(68	)
At December 31, 2017	—	6	232		238
Net book value
At December 31, 2017	1,469	5	495		1,969

Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of detailed information about property, plant and equipment [abstract]

Disclosure of detailed information about property, plant and equipment



	Computer hardware		Office equipment		Total
	£'000s		£'000s		£'000s
Cost
At January 1, 2016	43		36		79
Additions	13		—		13
Disposals	(39	)	(36	)	(75	)
At December 31, 2016	17		—		17
Accumulated depreciation
At January 1, 2016	39		27		66
Charge for the year	3		7		10
Disposals	(39	)	(34	)	(73	)
At December 31, 2016	3		—		3
Net book value
At December 31, 2016	14		—		14



	Computer hardware	Office equipment	Total
	£'000s	£'000s	£'000s
Cost
At January 1, 2017	17	—	17
Additions	9	—	9
At December 31, 2017	26	—	26
Accumulated depreciation
At January 1, 2017	3	—	3
Charge for the year	7	—	7
At December 31, 2017	10	—	10
Net book value
At December 31, 2017	16	—	16

Share Capital (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of share capital, reserves and other equity interest [Abstract]

Movements in the Company's share capital

The movements in the Company's share capital are summarized below:



Date	Description	Number of shares	Share Capital amounts in
Date	Description	Number of shares	£'000
January 1, 2016		20,198,469	1,010
July 29, 2016	Issuance of shares	31,115,926	1,556
September 12, 2016	Exercise of options	3,334	—
October 24, 2016	Exercise of options	3,334	—
December 28, 2016	Exercise of options	40,000	2
As at December 31, 2016		51,361,063	2,568
May 2, 2017	Issuance of shares	47,653,100	2,383
May 18, 2017	Issuance of shares	5,539,080	277
May 26, 2017	Issuance of shares	330,824	17
September 13, 2017	Exercise of options	133,333	6
December 31, 2017		105,017,400	5,251

Share-based payments charge (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of share-based payment arrangements [Abstract]

Disclosure of indirect measurement of fair value of goods or services received, share options granted during period



Issued in 2016	EMI Scheme		Unapproved Scheme
Options granted	32,000		1,670,000
Risk-free interest rate	1.42	%	0.23%-1.42%
Expected life of options	10 years		5.5-10 years
Annualized volatility	88.0	%	74.3% - 88.0%
Dividend rate	0.00	%	0.00	%
Vesting period	3 years		3 years

Issued in 2017	Unapproved Scheme		Restricted Stock Units
Options granted	4,656,828		1,052,236
Risk-free interest rate	0.29% - 0.62%		0.42%-0.62%
Expected life of options	5.5 – 7.0 years		5.5 – 7.0 years
Annualized volatility	71.3% - 73.3%		71.3% - 73.3%
Dividend rate	0.00	%	0.00	%
Vesting period	3 and 4 years		3 and 4 years

Disclosure of number and weighted average exercise prices of share options

The average fair value at grant date, by year of grant and plan, of the exercisable options as per December 31, 2017 is presented in the below table.



Year of issue	EMI Scheme (£)	Unapproved Scheme (£)	RSU (£)
2012	0.63 - 1.20	—	—
2013	0.83	0.79 - 0.95
2014	0.76	0.23 - 0.76
2015	0.57	0.57
2016	1.35	0.93 - 1.35
2017	—	0.84	1.33

Outstanding and exercisable share options by scheme as of December 31, 2017:



Plan	Outstanding	Exercisable	Weighted average exercise price in £ for Outstanding	Weighted average exercise price in £ for Exercisable
Unapproved	7,313,473	773,333	1.50	1.64
EMI	213,984	185,333	3.06	3.28
Total	7,527,457	958,666	1.54	1.95

As at December 31, 2017 there were no restricted share options exercisable (2016: nil) and there is no exercise price for restricted share options.



	Number of options		Weighted average exercise price (£)
At January 1, 2016	1,792,000		1.78
Options granted in 2016:
Employees	1,002,000		1.92
Directors	700,000		2.05
Options exercised in the year	(46,666	)	1.12
Options forfeited in the year	(150,001	)	1.24
Options expired in the year	(260,000	)	2.46
At December 31, 2016	3,037,333		1.87
Exercisable at December 31, 2016	846,667		2.25



	Number of options		Weighted average exercise price (£)
At January 1, 2017	3,037,333		1.87
Options granted in 2017:
Employees	3,150,846		1.32
Directors	1,505,982		1.32
Options exercised in the year	(133,333	)	1.10
Options forfeited in the year	—		—
Options expired in the year	(33,333	)	1.90
At December 31, 2017	7,527,495		1.53
Exercisable at December 31, 2017	797,333		2.04

The Company had the following share options movements in the year ended December 31, 2017:



Year of issue	Exercise price (£)	At January 1, 2017	Options granted	Options exercised		Options forfeited	Options expired		At December 31, 2017	Expiry date
2012	2.50 - 7.50	100,000	—	—		—	—		100,000	June 1, 2022
2013	2	100,000	—	—		—	—		100,000	April 15, 2023
2013	2.00	20,000	—	—		—	(20,000	)	—	June 1, 2023	*
2013	2.00	160,000	—	—		—	—		160,000	July 29, 2023
2014	1.75	110,000	—	—		—	—		110,000	May 15, 2024
2014	1.75	63,333	—	—		—	(13,333	)	50,000	May 15, 2024	*
2014	1.10 - 1.75	200,000	—	(133,333	)	—	—		66,667	August 6, 2018	**
2015	1.25	82,000	—	—		—	—		82,000	January 29, 2025	*
2015	1.25	510,000	—	—		—	—		510,000	January 29, 2025
2016	2	260,000	—	—		—	—		260,000	February 2, 2026
2016	2.00	22,000	—	—		—	—		22,000	February 2, 2026	*
2016	1.80	810,000	—	—		—	—		810,000	August 3, 2026
2016	1.89	300,000	—	—		—	—		300,000	September 13, 2026
2016	2.04	300,000	—	—		—	—		300,000	September 16, 2026
2017	1.32 - 1.525	—	4,656,828	—		—	—		4,656,828	April 26, 2027
Total		3,037,333	4,656,828	(133,333	)	—	(33,333	)	7,527,495


*	Options granted under the EMI Scheme.

* * Valued based on fair value of services received.

Disclosure of number and weighted average exercise prices of other equity instruments



		Number of RSUs
At January 1, 2017		—
Granted:
Employees		705,841
Directors		346,395
At December 31, 2017		1,052,236

The Company had the following Restricted Share Units movements in the year ended December 31, 2017:



Year of issue	Exercise price (£)	At January 1, 2017		Units granted		Units exercised		Units forfeited		Units expired		At December 31, 2017	Expiry date
2017		—		1,052,236		—		—		—		1,052,236	April 26, 2027
Total		—	—	1,052,236	—	—	—	—	—	—	—	1,052,236

Assumed contingent obligation related to the business combination (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of other provisions, contingent liabilities and contingent assets [Abstract]

Disclosure of contingent liabilities in business combination



	2016	2017
	£'000s	£'000s
January 1	594	802
Re-measurement of assumed contingent obligation	86	—
Impact of changes in foreign exchange rates	37	(23	)
Unwinding of discount factor	85	96
December 31	802	875



	2016	2017
	£'000s	£'000s
Change in value of the assumed contingent obligation	208	73
10% lower revenue assumption	202	72
10% higher revenue assumption	215	73
1% lower risk assumption	205	69
1% higher risk assumption	211	76

Warrants (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of share capital, reserves and other equity interest [Abstract]

Disclosure of indirect measurement of fair value of goods or services received, other equity instruments granted during period

The table below presents the assumptions in applying the Black-Scholes model to determine the fair value of the warrants.



	As of December 31, 2016			As of December 31, 2017
Shares available to be issued under warrants	12,446,370			12,401,262
Exercise price	£	1.7238		£	1.7238
Risk-free interest rate	0.088		%	0.420		%
Expected term to exercise	2.43 years			1.79 years
Annualized volatility	73.53		%	47.35		%
Dividend rate	0.00		%	0.00		%



	Derivative financial instrument		Derivative financial instrument
	2016		2017
	£'000s		£'000s
At January 1	—		7,923
On issuance of shares	8,991		—
Fair value adjustments recognized in profit or loss	(1,068	)	(6,650	)
At December 31	7,923		1,273

For the amount recognized at December 31, 2017, the effect when some of these underlying parameters would deviate up or down is presented in the below table.



	Volatility (up / down 10% pts)	Time to maturity (up / down 6 months)
	£'000s	£'000s
Variable up	1,921	1,677
Base case, reported fair value	1,273	1,273
Variable down	694	843

General information (Details) £ / shares in Units, $ / shares in Units, £ in Thousands, $ in Millions					1 Months Ended		12 Months Ended
	May 02, 2017 USD ($) shares	May 02, 2017 GBP (£) shares	Feb. 10, 2017	Feb. 08, 2017	May 31, 2017 USD ($)	May 31, 2017 GBP (£) £ / shares shares	Dec. 31, 2017 USD ($) subsidiary	Dec. 31, 2017 GBP (£) subsidiary £ / shares shares	Dec. 31, 2016 GBP (£)	May 31, 2017 $ / shares shares	May 26, 2017 shares	May 18, 2017 shares	Apr. 26, 2017 £ / shares shares	Apr. 26, 2017 $ / shares shares	Jul. 29, 2016 £ / shares shares
Disclosure of classes of share capital [line items]
Number of subsidiaries \| subsidiary							2	2
Consolidation of shares			0.02	0.02			0.02	0.02
Number of units issued (in shares)	47,653,100	47,653,100						1,555,796,345			330,824	5,539,080			31,115,926
Shares issued price (in dollars or pounds per share) \| £ / shares								£ 0.02873							£ 1.4365
Gross proceeds from the April 2017 Global Offering	$ 89.9	£ 70,000						£ 70,032	£ 0
Global Offering
Disclosure of classes of share capital [line items]
Number of units issued (in shares)													47,399,001	47,399,001
Gross proceeds from the April 2017 Global Offering					$ 89.9	£ 70,000	$ 89.9	70,000
IPO
Disclosure of classes of share capital [line items]
Number of units issued (in shares)													5,768,000	5,768,000
Shares issued price (in dollars or pounds per share) \| $ / shares														$ 13.50
Gross proceeds from the April 2017 Global Offering							$ 90.3	70,300
Private Placement
Disclosure of classes of share capital [line items]
Number of units issued (in shares)													1,255,001	1,255,001
Shares issued price (in dollars or pounds per share) \| £ / shares													£ 1.32
Gross proceeds from the April 2017 Global Offering \| £								80,000
Shareholder Private Placement
Disclosure of classes of share capital [line items]
Number of units issued (in shares)						254,099				254,099			254,099	254,099
Shares issued price (in dollars or pounds per share) \| £ / shares						£ 1.32							£ 1.32
Gross proceeds from the April 2017 Global Offering \| £						£ 300		£ 300
Over-Allotment Option
Disclosure of classes of share capital [line items]
Gross proceeds from the April 2017 Global Offering \| $					$ 9.9
Over-Allotment Option \| ADS
Disclosure of classes of share capital [line items]
Number of units issued (in shares)						733,738				733,738
Shares issued price (in dollars or pounds per share) \| $ / shares										$ 13.50
Over-Allotment Option \| Ordinary shares
Disclosure of classes of share capital [line items]
Number of units issued (in shares)						5,869,904				5,869,904

Accounting policies - Going concern (Details) £ in Thousands, $ in Millions				12 Months Ended
	May 02, 2017 USD ($)	May 02, 2017 GBP (£)	Jul. 29, 2016 GBP (£)	Dec. 31, 2017 GBP (£)	Dec. 31, 2016 GBP (£)	Dec. 31, 2015 GBP (£)	Dec. 31, 2014 GBP (£)
Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]
Loss for the year				£ (20,497)	£ (5,019)	£ (7,495)
Net assets				79,881	34,469	5,434	£ 12,526
Cash and cash equivalents and short term investments				80,300
Cash and cash equivalents				31,443	39,785	3,524	£ 9,968
Gross proceeds from the April 2017 Global Offering	$ 89.9	£ 70,000		70,032	0
Gross proceeds from issue of shares and warrants			£ 44,700	£ 0	£ 44,750	£ 0

- Definition

The total of income less expenses, excluding the components of other comprehensive income. [Refer: Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2017-01-01
-Paragraph 18
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_18_b&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 1
-IssueDate 2017-01-01
-Paragraph 24
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=1&date=2017-03-01&anchor=para_24_b&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 1
-IssueDate 2017-01-01
-Paragraph 32
-Subparagraph a
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=1&date=2017-03-01&anchor=para_32_a_ii&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 28
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_28_b&doctype=Standard
-URIDate 2017-03-09

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 23
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_23&doctype=Standard
-URIDate 2017-03-09

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 12
-IssueDate 2017-01-01
-Paragraph B10
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B10_b&doctype=Appendix&seq=2
-URIDate 2017-03-09

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 106
-Subparagraph d
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d_i&doctype=Standard
-URIDate 2017-03-09

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Note Effective on first application of IFRS 9
-Name IFRS
-Number 4
-IssueDate 2017-01-01
-Paragraph 39L
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=4&date=2017-03-01&anchor=para_39L_e&doctype=Standard
-URIDate 2017-03-09

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 81A
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_81A_a&doctype=Standard
-URIDate 2017-03-09

+ Details

Accounting policies - Description of property, plant and equipment useful life (Details)	12 Months Ended
	Dec. 31, 2017
Computer hardware
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment life	3 years
Office equipment
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment life	5 years

Accounting policies - Intangible assets and goodwill (Details)	12 Months Ended
	Dec. 31, 2017
Patents
Disclosure of detailed information about intangible assets [line items]
Estimated useful lives	10 years
Computer software
Disclosure of detailed information about intangible assets [line items]
Estimated useful lives	2 years

Accounting policies - Assumed contingent obligation related to the business combinations (Details) - GBP (£) £ in Thousands		12 Months Ended
	Sep. 19, 2006	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about business combination [line items]
Effective interest rate			12.00%
Rhinopharma Limited
Disclosure of detailed information about business combination [line items]
Consideration payable	£ 1,520
Effective interest rate	12.00%	12.00%

Financial Instruments - Summary quantitative data about entity's exposure to risk (Details) - Currency risk - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
USD \| Cash and cash equivalents
Disclosure of credit risk exposure [line items]
Cash deposits	£ 16,806	£ 10,631
USD \| Short Term Investments
Disclosure of credit risk exposure [line items]
Cash deposits	19,718	0
USD \| Trade and other payables
Disclosure of credit risk exposure [line items]
Cash deposits	276	305
EUR \| Cash and cash equivalents
Disclosure of credit risk exposure [line items]
Cash deposits	301	242
EUR \| Short Term Investments
Disclosure of credit risk exposure [line items]
Cash deposits	0	0
EUR \| Trade and other payables
Disclosure of credit risk exposure [line items]
Cash deposits	£ 403	£ 180

Financial Instruments - Disclosure of effect of changes in foreign exchange rates [text block] (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
EUR \| Strengthening
Disclosure of credit risk exposure [line items]
Profit or loss and equity	£ 35	£ 21
EUR \| Weakening
Disclosure of credit risk exposure [line items]
Profit or loss and equity	(35)	(21)
USD \| Strengthening
Disclosure of credit risk exposure [line items]
Profit or loss and equity	1,840	547
USD \| Weakening
Disclosure of credit risk exposure [line items]
Profit or loss and equity	£ (1,840)	£ (547)

Financial Instruments - Narrative (Details) - GBP (£)	12 Months Ended
Financial Instruments - Narrative (Details) - GBP (£)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of fair value measurement of assets [line items]
Cash deposits	£ 31,443,000	£ 39,785,000	£ 3,524,000	£ 9,968,000
Short-term deposits, not classified as cash equivalents	£ 48,819,000	0
Increase in interest rates	0.25%
Bottom of range
Disclosure of fair value measurement of assets [line items]
Trade payable term	30 years
Rates of interest	0.00%
Top of range
Disclosure of fair value measurement of assets [line items]
Trade payable term	45 years
Rates of interest	1.73%
Derivative financial instrument
Disclosure of fair value measurement of assets [line items]
Gains (losses) recognised in profit or loss, fair value measurement, liabilities	£ 6,650,000
Derivative financial instrument \| Level 3
Disclosure of fair value measurement of assets [line items]
Gains (losses) recognised in profit or loss, fair value measurement, liabilities	£ (6,650,000)	£ (1,068,000)

Financial Instruments - Disclosure Of Detailed Information About Cash And Cash Equivalents Placement Explanatory (Details) - GBP (£)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of financial assets [line items]
Cash and cash equivalents	£ 31,443,000	£ 39,785,000	£ 3,524,000	£ 9,968,000
Short term investments	48,819,000	0
Royal Bank of Scotland
Disclosure of financial assets [line items]
Cash and cash equivalents	16,623,000	11,287,000
Short term investments	15,316,000	0
Lloyds Bank
Disclosure of financial assets [line items]
Cash and cash equivalents	13,448,000	28,447,000
Short term investments	11,036,000	0
Standard Chartered
Disclosure of financial assets [line items]
Cash and cash equivalents	1,242,000	0
Short term investments	22,467,000	0
Wells Fargo
Disclosure of financial assets [line items]
Cash and cash equivalents	130,000	51,000
Short term investments	£ 0	£ 0

Financial Instruments - Disclosure of financial instruments by type of interest rate (Details) - Interest rate risk - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Floating interest rate
Disclosure of financial instruments by type of interest rate [line items]
Cash deposits	£ 25,720	£ 11,338
Fixed Interest rate
Disclosure of financial instruments by type of interest rate [line items]
Cash deposits	54,542	28,447
Cash deposits \| Floating interest rate
Disclosure of financial instruments by type of interest rate [line items]
Cash deposits	25,720	11,338
Cash deposits \| Fixed Interest rate
Disclosure of financial instruments by type of interest rate [line items]
Cash deposits	5,723	28,447
Short Term Investments \| Floating interest rate
Disclosure of financial instruments by type of interest rate [line items]
Cash deposits	0	0
Short Term Investments \| Fixed Interest rate
Disclosure of financial instruments by type of interest rate [line items]
Cash deposits	£ 48,819	£ 0

Financial Instruments - Disclosure of maturity analysis of undiscounted cash outflows to repurchase derecognised financial assets or amounts payable to transferee in respect of transferred assets (Details) - Liquidity risk - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
LESS THAN 1 YEAR
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	£ 7,154	£ 2,823
BETWEEN 1 AND 2 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
BETWEEN 2 AND 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
OVER 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	1,807	1,807
Trade payables \| LESS THAN 1 YEAR
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	1,214	719
Trade payables \| BETWEEN 1 AND 2 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Trade payables \| BETWEEN 2 AND 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Trade payables \| OVER 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Other payables \| LESS THAN 1 YEAR
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	74	54
Other payables \| BETWEEN 1 AND 2 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Other payables \| BETWEEN 2 AND 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Other payables \| OVER 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Accruals \| LESS THAN 1 YEAR
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	5,866	2,050
Accruals \| BETWEEN 1 AND 2 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Accruals \| BETWEEN 2 AND 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Accruals \| OVER 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Contingent obligation \| LESS THAN 1 YEAR
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Contingent obligation \| BETWEEN 1 AND 2 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Contingent obligation \| BETWEEN 2 AND 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	0	0
Contingent obligation \| OVER 5 YEARS
Disclosure of financial liabilities [line items]
Trade and other payables, undiscounted cash flows	£ 1,807	£ 1,807

Financial Instruments - Disclosure of fair value measurement of assets and liabilities (Details) - Derivative financial instrument - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of fair value measurement of assets [line items]
Financial assets	£ 1,273	£ 7,923
Level 3
Disclosure of fair value measurement of assets [line items]
Financial assets	£ 1,273	£ 7,923	£ 0

Financial Instruments - Disclosure of significant unobservable inputs used in fair value measurement of assets and liabilities (Details) - GBP (£) £ in Thousands		12 Months Ended
	Jul. 29, 2016	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of changes in fair value measurement, liabilities [abstract]
Initial recognition of derivative financial instrument	£ 9,000	£ 0	£ 8,991
Derivative financial instrument
Reconciliation of changes in fair value measurement, liabilities [abstract]
Beginning balance		7,923
Fair value adjustments recognized in profit and loss		6,650
Ending balance		1,273	7,923
Level 3 \| Derivative financial instrument
Reconciliation of changes in fair value measurement, liabilities [abstract]
Beginning balance		7,923	0
Initial recognition of derivative financial instrument		0	8,991
Fair value adjustments recognized in profit and loss		(6,650)	(1,068)
Ending balance		£ 1,273	£ 7,923

Financial Instruments - Change in liabilities arising from financing activities (Details) - Derivative financial instrument £ in Thousands	12 Months Ended
	Dec. 31, 2017 GBP (£)
Changes in fair value measurement, liabilities [abstract]
Beginning balance	£ 7,923
Fair value adjustments - non cash	(6,650)
Ending balance	£ 1,273

Critical accounting estimates and judgments (Details) £ / shares in Units, £ in Thousands		12 Months Ended
	Sep. 19, 2006	Dec. 31, 2017 GBP (£) £ / shares shares	Dec. 31, 2016 GBP (£) shares	Dec. 31, 2015 GBP (£)	May 26, 2017 shares	May 18, 2017 shares	May 02, 2017 shares	Jul. 31, 2016 shares warrant	Jul. 29, 2016 shares warrant £ / shares
Disclosure of detailed information about business combination [line items]
Assumed contingent obligation		£ 875	£ 802	£ 594
Discount percent			12.00%
Number of units issued (in shares) \| shares		1,555,796,345			330,824	5,539,080	47,653,100		31,115,926
Placing price (in pounds per unit) \| £ / shares		£ 0.02873							£ 1.4365
Number of ordinary shares (in shares) \| shares								1	1
Number warrants (in warrants) \| warrant								1	1
Number of shares subscribed from warrant maximum (in shares) \| shares		622,318,538
Research and development expense		£ 23,717	£ 4,522	£ 7,270
Rhinopharma Limited
Disclosure of detailed information about business combination [line items]
Reported change to the value of the liability		£ 73	£ 200
Discount percent	12.00%	12.00%
Warrants
Disclosure of detailed information about business combination [line items]
Number of shares subscribed from warrant maximum (in shares) \| shares		12,401,262	12,446,370						12,446,370
Clinical Research Organization
Disclosure of detailed information about business combination [line items]
Research and development expense		£ 18,500
Accruals		4,600
Prepayments		£ 500

Earnings per share (Details) - £ / shares	12 Months Ended
Earnings per share (Details) - £ / shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of earnings per share [Abstract]
Basic loss per share (pounds per share)	£ 0.234	£ 0.150	£ 37.100
Weighted average number of ordinary shares (in shares)	87,748,031	33,499,413	20,198,469

Operating loss - Description Of Operating Loss (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Research and development costs:
Total research and development costs	£ 23,717	£ 4,522	£ 7,270
General and administrative costs:
Total general and administrative costs	6,039	2,498	1,706
Operating loss	29,756	7,020	8,976
Research and development costs
Research and development costs:
Employee benefits (note 8)	3,435	2,037	1,322
Legal, professional consulting and listing fees	331	0	0
Loss on disposal of patents	0	0	136
Other research and development expenses	19,840	2,434	5,769
Total research and development costs	23,717	4,522	7,270
General and administrative costs:
Employee benefits (note 8)	3,435	2,037	1,322
Legal, professional consulting and listing fees	331	0	0
Research and development costs \| Patents
Research and development costs:
Amortization	111	51	43
General and administrative costs:
Amortization	111	51	43
General and administrative costs
Research and development costs:
Employee benefits (note 8)	2,857	865	625
Legal, professional consulting and listing fees	2,045	884	608
General and administrative costs:
Employee benefits (note 8)	2,857	865	625
Legal, professional consulting and listing fees	2,045	884	608
Loss on disposal of property, plant and equipment (note 13)	0	3	0
Depreciation of property, plant and equipment (note 13)	7	10	10
Operating lease charge — land and buildings	294	169	157
Loss on variations in foreign exchange rate	36	139	21
Other general and administrative expenses	795	427	285
Total general and administrative costs	6,039	2,498	1,706
Operating loss	29,756	7,020	8,976
General and administrative costs \| Computer software
Research and development costs:
Amortization	5	1	0
General and administrative costs:
Amortization	£ 5	£ 1	£ 0

Directors' emoluments and staff costs (Details)	12 Months Ended
Directors' emoluments and staff costs (Details)	Dec. 31, 2017 GBP (£) employee	Dec. 31, 2016 GBP (£) employee	Dec. 31, 2015 GBP (£) employee
Disclosure of transactions between related parties [line items]
The average number of employees (excluding directors) of the Company during the year: \| employee	12.0	7.0	8.0
Aggregate emoluments of directors:
Share-based payment charge	£ 2,920,000	£ 580,000
Aggregate other staff costs:
Share-based payment charge	2,920,000	580,000
Post-employment benefit expense, defined contribution plans	55,000	30,000	£ 53,000
Prepaid or accrued contributions	0	0	0
Directors
Aggregate emoluments of directors:
Salaries and other short-term employee benefits	897,000	951,000	722,000
Social security costs	103,000	118,000	132,000
Incremental payment for additional services	0	44,000	89,000
Other pension costs	17,000	19,000	38,000
Total directors' emoluments	1,017,000	1,132,000	981,000
Share-based payment charge	1,037,000	257,000	232,000
Directors' emoluments including share-based payment charge	2,054,000	1,389,000	1,213,000
Aggregate other staff costs:
Social security costs	103,000	118,000	132,000
Incremental payment for additional services	0	44,000	89,000
Share-based payment charge	1,037,000	257,000	232,000
Other pension costs	17,000	19,000	38,000
Other staff
Aggregate emoluments of directors:
Social security costs	182,000	98,000	42,000
Incremental payment for additional services	0	58,000	0
Other pension costs	38,000	11,000	15,000
Share-based payment charge	1,882,000	319,000	137,000
Aggregate other staff costs:
Wages and salaries	2,136,000	1,027,000	540,000
Social security costs	182,000	98,000	42,000
Incremental payment for additional services	0	58,000	0
Share-based payment charge	1,882,000	319,000	137,000
Other pension costs	38,000	11,000	15,000
Total other staff costs	£ 4,238,000	£ 1,513,000	£ 734,000
Research and Development
Disclosure of transactions between related parties [line items]
The average number of employees (excluding directors) of the Company during the year: \| employee	7.0	5.0	5.0
General and Administrative
Disclosure of transactions between related parties [line items]
The average number of employees (excluding directors) of the Company during the year: \| employee	5.0	2.0	3.0

Finance income and expense (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finance income:
Interest received on cash balances	£ 345	£ 86	£ 45
Foreign exchange gain on translating foreign currency denominated bank balances	0	687	0
Fair value adjustment on derivative financial instruments (note 19)	6,650	1,068	0
Other Income	23	0	0
Total finance income	7,018	1,841	45
Finance expense:
Transaction costs allocated to the issue of warrants (note 19)	0	586	0
Foreign exchange loss on translating foreign currency denominated balances	2,392	0	0
Remeasurement of assumed contingent arrangement (note 18)	0	122	10
Unwinding of discount factor and foreign exchange movements related to the assumed contingent arrangement (note 18)	73	86	63
Total finance expense	£ 2,465	£ 794	£ 73

Taxation - Disclosure of major components of tax expense (income) (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax:
Adjustment in respect of prior periods	£ (6)	£ (16)	£ 11
Total tax credit	(4,706)	(954)	(1,509)
Factors affecting the tax charge for the year
Loss on ordinary activities	(25,203)	(5,973)	(9,002)
Multiplied by standard rate of corporation tax of 19.25% (2016: 20% and 2015: 20.25%)	£ (4,852)	£ (1,195)	£ (1,823)
Standard rate of corporation tax	19.25%	20.00%	20.25%
Effects of:
Non-deductible expenses	£ 675	£ 292	£ 114
Fair value adjustment on derivative financial instruments	(1,280)	(214)	0
Research and development incentive	(2,116)	(427)	(600)
Temporary differences not recognized	(2)	(4)	(1)
Difference in overseas tax rates	136	56	0
Tax losses carried forward not recognized	2,739	554	790
Adjustment in respect of prior periods	(6)	(16)	11
Total tax credit	(4,706)	(954)	(1,509)
UK
Current tax:
UK tax credit	(5,006)	(1,067)	(1,520)
US
Current tax:
UK tax credit	£ 306	£ 129	£ 0
Factors affecting the tax charge for the year
Standard rate of corporation tax	35.00%	35.00%	35.00%

Taxation - Narrative (Details) - GBP (£) £ in Thousands	12 Months Ended
Taxation - Narrative (Details) - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Standard rate of corporation tax	19.25%	20.00%	20.25%
Unrecognized deferred tax asset percent	17.00%	17.00%
Unrecognized deferred tax asset	£ 5,430	£ 3,150
U.S. federal tax
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Standard rate of corporation tax	35.00%	35.00%	35.00%

Taxation - Disclosure of temporary difference, unused tax losses and unused tax credits (Details) - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of income tax [Abstract]
Deferred tax assets	£ 250	£ 250
Deferred tax liabilities	(250)	(250)
Net balances	£ 0	£ 0

Goodwill (Details) - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about intangible assets [abstract]
Goodwill at January 1 and December 31	£ 441	£ 441

Intangible assets - Disclosure of reconciliation of changes in intangible assets and goodwill (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about intangible assets [line items]
Beginning balance	£ 1,877
Ending balance	1,969	£ 1,877
Cost
Disclosure of detailed information about intangible assets [line items]
Beginning balance	2,067	1,976
Additions	208	115
Disposals	(68)	(24)
Ending balance	2,207	2,067
Accumulated depreciation
Disclosure of detailed information about intangible assets [line items]
Beginning balance	190	162
Disposals	(68)	(24)
Charge for year	116	52
Ending balance	238	190
IP R&D
Disclosure of detailed information about intangible assets [line items]
Beginning balance	1,469
Ending balance	1,469	1,469
IP R&D \| Cost
Disclosure of detailed information about intangible assets [line items]
Beginning balance	1,469	1,469
Additions	0	0
Disposals	0	0
Ending balance	1,469	1,469
Computer software
Disclosure of detailed information about intangible assets [line items]
Beginning balance	5
Ending balance	5	5
Computer software \| Cost
Disclosure of detailed information about intangible assets [line items]
Beginning balance	6	25
Additions	5	5
Disposals	0	(24)
Ending balance	11	6
Computer software \| Accumulated depreciation
Disclosure of detailed information about intangible assets [line items]
Beginning balance	1	24
Disposals	0	(24)
Charge for year	5	1
Ending balance	6	1
Patents
Disclosure of detailed information about intangible assets [line items]
Beginning balance	403
Ending balance	495	403
Patents \| Cost
Disclosure of detailed information about intangible assets [line items]
Beginning balance	592	482
Additions	203	110
Disposals	(68)	0
Ending balance	727	592
Patents \| Accumulated depreciation
Disclosure of detailed information about intangible assets [line items]
Beginning balance	189	138
Disposals	(68)	0
Charge for year	111	51
Ending balance	£ 232	£ 189

Intangible assets - Narrative (Details) - GBP (£)	12 Months Ended
Intangible assets - Narrative (Details) - GBP (£)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of detailed information about intangible assets [line items]
Market capitalization	£ 109,700,000	£ 80,000,000
Net assets	79,881,000	£ 34,469,000	£ 5,434,000	£ 12,526,000
Impairment	£ 0
Patents
Disclosure of detailed information about intangible assets [line items]
Amortization period	10 years

Property, plant and equipment (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cost
Property, plant and equipment beginning balance	£ 14
Property, plant and equipment ending balance	16	£ 14
Accumulated depreciation
Property, plant and equipment beginning balance	14
Property, plant and equipment ending balance	16	14
Net book value
Property plant and equipment	14	14
Cost
Cost
Property, plant and equipment beginning balance	17	79
Additions	9	13
Disposals		(75)
Property, plant and equipment ending balance	26	17
Accumulated depreciation
Property, plant and equipment beginning balance	17	79
Disposals		(75)
Property, plant and equipment ending balance	26	17
Net book value
Property plant and equipment	17	79
Accumulated depreciation
Cost
Property, plant and equipment beginning balance	3	66
Disposals		(73)
Property, plant and equipment ending balance	10	3
Accumulated depreciation
Property, plant and equipment beginning balance	3	66
Charge for the year	7	10
Disposals		(73)
Property, plant and equipment ending balance	10	3
Net book value
Property plant and equipment	3	66
Computer hardware
Cost
Property, plant and equipment beginning balance	14
Property, plant and equipment ending balance	16	14
Accumulated depreciation
Property, plant and equipment beginning balance	14
Property, plant and equipment ending balance	16	14
Net book value
Property plant and equipment	14	14
Computer hardware \| Cost
Cost
Property, plant and equipment beginning balance	17	43
Additions	9	13
Disposals		(39)
Property, plant and equipment ending balance	26	17
Accumulated depreciation
Property, plant and equipment beginning balance	17	43
Disposals		(39)
Property, plant and equipment ending balance	26	17
Net book value
Property plant and equipment	17	43
Computer hardware \| Accumulated depreciation
Cost
Property, plant and equipment beginning balance	3	39
Disposals		(39)
Property, plant and equipment ending balance	10	3
Accumulated depreciation
Property, plant and equipment beginning balance	3	39
Charge for the year	7	3
Disposals		(39)
Property, plant and equipment ending balance	10	3
Net book value
Property plant and equipment	3	39
Office equipment
Cost
Property, plant and equipment beginning balance	0
Property, plant and equipment ending balance	0	0
Accumulated depreciation
Property, plant and equipment beginning balance	0
Property, plant and equipment ending balance	0	0
Net book value
Property plant and equipment	0	0
Office equipment \| Cost
Cost
Property, plant and equipment beginning balance	0	36
Additions	0	0
Disposals		(36)
Property, plant and equipment ending balance	0	0
Accumulated depreciation
Property, plant and equipment beginning balance	0	36
Disposals		(36)
Property, plant and equipment ending balance	0	0
Net book value
Property plant and equipment	0	36
Office equipment \| Accumulated depreciation
Cost
Property, plant and equipment beginning balance	0	27
Disposals		(34)
Property, plant and equipment ending balance	0	0
Accumulated depreciation
Property, plant and equipment beginning balance	0	27
Charge for the year	0	7
Disposals		(34)
Property, plant and equipment ending balance	0	0
Net book value
Property plant and equipment	£ 0	£ 27

Prepayments and other receivables (Details) - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Subclassifications of assets, liabilities and equities [abstract]
Prepayments	£ 1,138	£ 1,361
Deferred IPO costs	0	1,527
Other receivables	672	71
Total prepayments and other receivables	£ 1,810	£ 2,959

Share Capital - Movements in the Company's share capital (Details) £ in Thousands									12 Months Ended
	Sep. 13, 2017 GBP (£) shares	May 26, 2017 GBP (£) shares	May 18, 2017 GBP (£) shares	May 02, 2017 GBP (£) shares	Dec. 28, 2016 GBP (£) shares	Oct. 24, 2016 shares	Sep. 12, 2016 shares	Jul. 29, 2016 GBP (£) shares	Dec. 31, 2017 GBP (£) shares	Dec. 31, 2016 GBP (£) shares
Number of shares
Beginning balance (in shares) \| shares									51,361,063	20,198,469
Issuance of shares (in shares) \| shares		330,824	5,539,080	47,653,100				31,115,926	1,555,796,345
Exercise of options (in shares) \| shares	133,333				40,000	3,334	3,334		133,333	46,666
Ending balance (in shares) \| shares									105,017,400	51,361,063
Share Capital amounts in
Beginning balance \| £									£ 2,568	£ 1,010
Issuance of shares \| £		£ 17	£ 277	£ 2,383				£ 1,556	70,325	35,707
Exercise of options \| £	£ 6				£ 2
Ending balance \| £									£ 5,251	£ 2,568

Share Capital - Narrative (Details) £ / shares in Units, $ / shares in Units, $ in Millions											1 Months Ended		12 Months Ended
	Sep. 13, 2017 GBP (£) shares £ / shares	May 02, 2017 USD ($) shares	May 02, 2017 GBP (£) shares	Apr. 26, 2017 GBP (£) £ / shares shares	Feb. 10, 2017	Feb. 08, 2017 £ / shares	Dec. 28, 2016 shares	Oct. 24, 2016 shares	Sep. 12, 2016 shares	Jul. 29, 2016 GBP (£) shares warrant £ / shares	May 31, 2017 USD ($)	May 31, 2017 GBP (£) £ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2017 GBP (£) shares £ / shares	Dec. 31, 2016 GBP (£) shares	Dec. 31, 2015 GBP (£) shares	May 31, 2017 $ / shares shares	May 26, 2017 shares	May 18, 2017 shares	Apr. 26, 2017 $ / shares shares	Feb. 07, 2017 £ / shares	Jul. 31, 2016 shares warrant
Disclosure of classes of share capital [line items]
Consolidation of shares					0.02	0.02							0.02	0.02
Price per share (in pounds per share) \| £ / shares						£ 0.05								£ 0.05							£ 0.001
Number of shares authorized														200,000,000
Share capital \| £														£ 10,000,000
Number of shares allotted, unrestricted, called up and fully paid (in shares)														105,017,400	51,361,063	20,198,469
Number of ordinary shares in issue (in shares)		47,653,100	47,653,100							31,115,926				1,555,796,345				330,824	5,539,080
Shares issued price (in dollars or pounds per share) \| £ / shares										£ 1.4365				£ 0.02873
Gross proceeds from the April 2017 Global Offering		$ 89.9	£ 70,000,000											£ 70,032,000	£ 0
Finance expense from movements in exchange rates \| £				£ 439,000
Saving on commission payable \| £				31,000
Finance expense \| £				£ 408,000						£ 2,900,000				£ 7,453,000	£ 2,325,000
Number of shares subscribed from warrant maximum (in shares)	133,333						40,000	3,334	3,334				133,333	133,333	46,666
Exercise price (pounds per share) \| £ / shares	£ 1.10
Proceeds from warrant exercise \| £	£ 147,000
Number of ordinary shares (in shares)										1												1
Number warrants (in warrants) \| warrant										1												1
Number of shares subscribed (in shares)										0.4
Exercise price percent										120.00%
Gross proceeds from issue of shares and warrants \| £										£ 44,700,000				£ 0	£ 44,750,000	£ 0
Ordinary shares
Disclosure of classes of share capital [line items]
Finance expense \| £										£ 2,300,000
Global Offering
Disclosure of classes of share capital [line items]
Number of ordinary shares in issue (in shares)				47,399,001																47,399,001
Gross proceeds from the April 2017 Global Offering											$ 89.9	£ 70,000,000	$ 89.9	70,000,000
IPO
Disclosure of classes of share capital [line items]
Number of ordinary shares in issue (in shares)				5,768,000																5,768,000
Shares issued price (in dollars or pounds per share) \| $ / shares																				$ 13.50
Gross proceeds from the April 2017 Global Offering													$ 90.3	70,300,000
Private Placement
Disclosure of classes of share capital [line items]
Number of ordinary shares in issue (in shares)				1,255,001																1,255,001
Shares issued price (in dollars or pounds per share) \| £ / shares				£ 1.32
Gross proceeds from the April 2017 Global Offering \| £														80,000,000
Over-Allotment Option
Disclosure of classes of share capital [line items]
Gross proceeds from the April 2017 Global Offering \| $											$ 9.9
Over-Allotment Option \| ADS
Disclosure of classes of share capital [line items]
Number of ordinary shares in issue (in shares)												733,738					733,738
Shares issued price (in dollars or pounds per share) \| $ / shares																	$ 13.50
Over-Allotment Option \| Ordinary shares
Disclosure of classes of share capital [line items]
Number of ordinary shares in issue (in shares)												5,869,904					5,869,904
Shareholder Private Placement
Disclosure of classes of share capital [line items]
Number of ordinary shares in issue (in shares)				254,099								254,099					254,099			254,099
Shares issued price (in dollars or pounds per share) \| £ / shares				£ 1.32								£ 1.32
Gross proceeds from the April 2017 Global Offering \| £												£ 300,000		£ 300,000

Share-based payments charge - Narrative (Details)	12 Months Ended
Share-based payments charge - Narrative (Details)	Dec. 31, 2017 GBP (£) shares year vesting_method hour	Dec. 31, 2016 GBP (£) shares year
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment charge \| £	£ 2,920,000	£ 580,000
Number of share options granted (in shares)	4,656,828
Fair value of equity instruments \| £	£ 5,330,000	£ 1,930,000
Weighted average remaining contractual life of outstanding share options \| year	8.6	8.2
Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period		3 years
Number of vesting methods \| vesting_method	2
Exercise period	10 years
Number of share options granted (in shares)	4,656,828	1,670,000
EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period		3 years
Exercise period	10 years
Hours worked per week (at least) \| hour	25
Percent of working time (at least)	75.00%
Number of share options granted (in shares)	0	32,000
Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of vesting methods \| vesting_method	2
Number of share options granted (in shares)	1,052,236	0
Number of other equity instruments exercisable in share-based payment arrangement (in shares)	0	0
Granted, Weighted average exercise price in £ for Outstanding (pounds per share) \| £	£ 1.32
Bottom of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	3 years
Bottom of range \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	3 years
Top of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	4 years
Top of range \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	4 years
Method one, tranche one \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	1 year
Vesting portion	0.3333
Method one, tranche one \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	1 year
Vesting portion	0.3333
Method one, tranche two \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	2 years
Vesting portion	0.3333
Method one, tranche two \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	2 years
Vesting portion	0.3333
Method one, tranche three \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	3 years
Vesting portion	0.3333
Method one, tranche three \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	3 years
Vesting portion	0.3333
Method two, tranche one \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting portion	0.25
Method two, tranche one \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting portion	0.25
Method two, tranche two \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting portion	0.25
Method two, tranche two \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	2 years
Vesting portion	0.25
Method two, tranche three \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting portion	0.25
Method two, tranche three \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	3 years
Vesting portion	0.25
Method two, tranche four \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	4 years
Vesting portion	0.25
Method two, tranche four \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	4 years
Vesting portion	0.25
Advisor Options \| Bottom of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise period	1 year
Advisor Options \| Top of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise period	2 years

Share-based payments charge - Disclosure of indirect measurement of fair value of goods or services received, share options granted during period (Details)	12 Months Ended
	Dec. 31, 2017 shares year	Dec. 31, 2016 shares year
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares) \| shares	4,656,828
EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares) \| shares	0	32,000
Risk-free interest rate		1.42%
Expected life of options		10
Annualized volatility		88.00%
Dividend rate		0.00%
Vesting period		3 years
Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares) \| shares	4,656,828	1,670,000
Dividend rate	0.00%	0.00%
Vesting period		3 years
Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares) \| shares	1,052,236	0
Dividend rate	0.00%
Bottom of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	0.29%	0.23%
Expected life of options	5.5	5.5
Annualized volatility	71.30%	74.30%
Vesting period	3 years
Bottom of range \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	0.42%
Expected life of options	5.5
Annualized volatility	71.30%
Vesting period	3 years
Top of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	0.62%	1.42%
Expected life of options	7.0	10
Annualized volatility	73.30%	88.00%
Vesting period	4 years
Top of range \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	0.62%
Expected life of options	7.0
Annualized volatility	73.30%
Vesting period	4 years

Share-based payments charge - Share options movements (Details)					12 Months Ended
	Sep. 13, 2017 GBP (£) shares	Dec. 28, 2016 GBP (£) shares	Oct. 24, 2016 shares	Sep. 12, 2016 shares	Dec. 31, 2017 GBP (£) shares	Dec. 31, 2016 shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £	£ 6,000	£ 2,000
Beginning balance (in shares)					3,037,333	1,792,000
Options granted (in shares)					4,656,828
Options exercised (in shares)	(133,333)	(40,000)	(3,334)	(3,334)	(133,333)	(46,666)
Options forfeited (in shares)					0	150,001
Options expired (in shares)					(33,333)	(260,000)
Ending balance (in shares)					7,527,495	3,037,333
Year Of Issue, 2012, Expiry Date June 1, 2022
Disclosure of terms and conditions of share-based payment arrangement [line items]
Beginning balance (in shares)					100,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					100,000	100,000
Year Of Issue, 2012, Expiry Date June 1, 2022 \| Bottom of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2.50
Year Of Issue, 2012, Expiry Date June 1, 2022 \| Top of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					7.50
Year Of Issue, 2013, Expiry Date April 15, 2023
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2
Beginning balance (in shares)					100,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					100,000	100,000
Year Of Issue, 2013, Expiry Date July 29, 2023
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2.00
Beginning balance (in shares)					160,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					160,000	160,000
Year Of Issue, 2014, Expiry Date May 15, 2024
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.75
Beginning balance (in shares)					110,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					110,000	110,000
Year Of Issue, 2014, Expiry Date August 6, 2018
Disclosure of terms and conditions of share-based payment arrangement [line items]
Beginning balance (in shares)					200,000
Options granted (in shares)					0
Options exercised (in shares)					(133,333)
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					66,667	200,000
Year Of Issue, 2014, Expiry Date August 6, 2018 \| Bottom of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.10
Year Of Issue, 2014, Expiry Date August 6, 2018 \| Top of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					1.75
Year Of Issue, 2015, Expiry Date January 29, 2025
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.25
Beginning balance (in shares)					510,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					510,000	510,000
Year Of Issue, 2016, Expiry Date February 2, 2026
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2
Beginning balance (in shares)					260,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					260,000	260,000
Year Of Issue, 2016, Expiry Date August 3, 2026
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.80
Beginning balance (in shares)					810,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					810,000	810,000
Year Of Issue, 2016, Expiry Date September 13, 2026
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.89
Beginning balance (in shares)					300,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					300,000	300,000
Year Of Issue, 2016, Expiry Date September 16, 2026
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2.04
Beginning balance (in shares)					300,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					300,000	300,000
Year Of Issue, 2017, Expiry Date April 26, 2027
Disclosure of terms and conditions of share-based payment arrangement [line items]
Beginning balance (in shares)					0
Options granted (in shares)					4,656,828
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					4,656,828	0
Year Of Issue, 2017, Expiry Date April 26, 2027 \| Bottom of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.32
Year Of Issue, 2017, Expiry Date April 26, 2027 \| Top of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.525
EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares)					0	32,000
Ending balance (in shares)					213,984
EMI Scheme \| Year Of Issue, 2013, Expiry Date June 1, 2023
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2.00
Beginning balance (in shares)					20,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					(20,000)
Ending balance (in shares)					0	20,000
EMI Scheme \| Year Of Issue, 2014, Expiry Date May 15, 2024
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.75
Beginning balance (in shares)					63,333
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					(13,333)
Ending balance (in shares)					50,000	63,333
EMI Scheme \| Year Of Issue, 2015, Expiry Date January 29, 2025
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 1.25
Beginning balance (in shares)					82,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					82,000	82,000
EMI Scheme \| Year Of Issue, 2016, Expiry Date February 2, 2026
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise of options \| £					£ 2.00
Beginning balance (in shares)					22,000
Options granted (in shares)					0
Options exercised (in shares)					0
Options forfeited (in shares)					0
Options expired (in shares)					0
Ending balance (in shares)					22,000	22,000

Share-based payments charge - Disclosure of number and weighted average exercise prices of other equity instruments (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2017 shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Beginning balance (in shares)	0
Options granted (in shares)	1,052,236
Options exercised (in shares)	0
Options forfeited (in shares)	0
Options expired (in shares)	0
Ending balance (in shares)	1,052,236
Year Of Issue, 2017, Expiry Date April 26, 2027
Disclosure of terms and conditions of share-based payment arrangement [line items]
Beginning balance (in shares)	0
Options granted (in shares)	1,052,236
Options exercised (in shares)	0
Options forfeited (in shares)	0
Options expired (in shares)	0
Ending balance (in shares)	1,052,236

Share-based payments charge - Average fair value at grant date, by year of grant and plan, of the exercisable options (Details)	Dec. 31, 2017 USD ($)
2012 \| Bottom of range \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	$ 0.63
2012 \| Top of range \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	1.20
2013 \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.83
2013 \| Bottom of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.79
2013 \| Top of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.95
2014 \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.76
2014 \| Bottom of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.23
2014 \| Top of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.76
2015 \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.57
2015 \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.57
2016 \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	1.35
2016 \| Bottom of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.93
2016 \| Top of range \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	1.35
2017 \| EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.00
2017 \| Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	0.84
2017 \| Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Average fair value at grant date (pounds per share)	$ 1.33

Share-based payments charge - Outstanding and exercisable share options by scheme (Details)	Dec. 31, 2017 GBP (£) shares	Dec. 31, 2016 GBP (£) shares	Dec. 31, 2015 GBP (£) shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding (in shares) \| shares	7,527,495	3,037,333	1,792,000
Exercisable (in shares) \| shares	797,333	846,666.76
Weighted average exercise price in £ for Outstanding (pounds per share) \| £	£ 1.53	£ 1.87	£ 1.78
Weighted average exercise price in £ for Exercisable (pounds per share) \| £	£ 2.04	£ 2.25
Unapproved Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding (in shares) \| shares	7,313,473
Exercisable (in shares) \| shares	773,333
Weighted average exercise price in £ for Outstanding (pounds per share) \| £	£ 1.50
Weighted average exercise price in £ for Exercisable (pounds per share) \| £	£ 1.64
EMI Scheme
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding (in shares) \| shares	213,984
Exercisable (in shares) \| shares	185,333
Weighted average exercise price in £ for Outstanding (pounds per share) \| £	£ 3.06
Weighted average exercise price in £ for Exercisable (pounds per share) \| £	£ 3.28
Unapproved And EMI Share Option Schemes [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding (in shares) \| shares	7,527,457,000
Exercisable (in shares) \| shares	958,666,000
Weighted average exercise price in £ for Outstanding (pounds per share) \| £	£ 1.54
Weighted average exercise price in £ for Exercisable (pounds per share) \| £	£ 1.95

Share-based payments charge - Number of options granted, expired and the weighted average exercise price of options (Details)					12 Months Ended
	Sep. 13, 2017 shares	Dec. 28, 2016 shares	Oct. 24, 2016 shares	Sep. 12, 2016 shares	Dec. 31, 2017 GBP (£) shares	Dec. 31, 2016 GBP (£) shares
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Beginning balance (in shares)					3,037,333	1,792,000
Options granted (in shares)					4,656,828
Options exercised (in shares)	(133,333)	(40,000)	(3,334)	(3,334)	(133,333)	(46,666)
Options forfeited (in shares)					0	(150,001)
Options expired (in shares)					(33,333)	(260,000)
Ending balance (in shares)					7,527,495	3,037,333
Exercisable (in shares)					797,333	846,666.76
Beginning balance, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					£ 1.87	£ 1.78
Exercised, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					1.10	1.12
Forfeited, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					0.00	1.24
Expired, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					1.90	2.46
Ending balance, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					1.53	1.87
Weighted average exercise price in £ for Exercisable (pounds per share) \| £					£ 2.04	£ 2.25
Employees
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Options granted (in shares)					3,150,846	1,002,000
Granted, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					£ 1.32	£ 1.92
Directors
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Options granted (in shares)					1,505,982	700,000
Granted, Weighted average exercise price in £ for Outstanding (pounds per share) \| £					£ 1.32	£ 2.05

Share-based payments charge - Equity instruments other than options granted (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2017 shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Beginning balance (in shares)	0
Options granted (in shares)	1,052,236
Ending balance (in shares)	1,052,236
Employees
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares)	705,841
Directors
Disclosure of terms and conditions of share-based payment arrangement [line items]
Options granted (in shares)	346,395

Trade and other payables (Details) - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Subclassifications of assets, liabilities and equities [abstract]
Trade payables	£ 1,214	£ 719
Other payables	74	54
Accruals	5,866	2,050
Total trade and other payables	£ 7,154	2,823
Accruals related to offering expenses		£ 890

Assumed contingent obligation related to the business combination - Narrative (Details) - GBP (£) £ in Thousands		12 Months Ended
	Sep. 19, 2006	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about business combination [line items]
Assumed contingent obligation		£ 875	£ 802	£ 594
Discount percent			12.00%
Rhinopharma Limited
Disclosure of detailed information about business combination [line items]
Increase in value of the assumed contingent obligation		£ 73	£ 208
Discount percent	12.00%	12.00%
Reported change to the value of the liability		£ 73	£ 200

Assumed contingent obligation related to the business combination - Reconciliation of changes in contingent liabilities (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of changes in contingent liabilities recognised in business combination [abstract]
Beginning balance	£ 802	£ 594
Re-measurement of assumed contingent obligation	0	86
Impact of changes in foreign exchange rates	(23)	37
Unwinding of discount factor	96	85
Ending balance	£ 875	£ 802

Assumed contingent obligation related to the business combination - Reported change to the value of the liability (Details) - Rhinopharma Limited - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about business combination [line items]
Change in value of the assumed contingent obligation	£ 73	£ 208
10% lower revenue assumption	72	202
10% higher revenue assumption	73	215
1% lower risk assumption	69	205
1% higher risk assumption	£ 76	£ 211
Revenue assumption, % lower	10.00%
Revenue assumption, % higher	10.00%
Risk assumption, % lower	1.00%
Risk assumption, % higher	1.00%

Warrants - Narrative (Details) £ / shares in Units, £ in Thousands					12 Months Ended
	Apr. 26, 2017 GBP (£)	Feb. 10, 2017	Feb. 08, 2017	Jul. 29, 2016 GBP (£) shares warrant £ / shares	Dec. 31, 2017 GBP (£) shares £ / shares	Dec. 31, 2016 GBP (£) shares £ / shares	Dec. 31, 2015 GBP (£)	Sep. 13, 2017 £ / shares	May 26, 2017 shares	May 18, 2017 shares	May 02, 2017 shares	Jul. 31, 2016 shares warrant
Disclosure of classes of share capital [line items]
Number of units issued (in shares) \| shares				31,115,926	1,555,796,345				330,824	5,539,080	47,653,100
Placing price (in pounds per unit) \| £ / shares				£ 1.4365	£ 0.02873
Number of ordinary shares (in shares) \| shares				1								1
Number warrants (in warrants) \| warrant				1								1
Number of shares subscribed (in shares) \| shares				0.4
Exercise price percent				120.00%
Exercise price (pounds per share) \| £ / shares								£ 1.10
Number of shares subscribed from warrant maximum (in shares) \| shares					622,318,538
Change in fair value \| £				£ 9,000	£ 0	£ 8,991
Warrant proceeds \| £				35,700
Transaction costs allocated to the issue of warrants (note 19) \| £	£ 408			£ 2,900	£ 7,453	£ 2,325
Warrants forfeited (in shares) \| shares					0	150,001
Consolidation of shares		0.02	0.02		0.02
Exercise price (pence per share) \| £ / shares					£ 0.034476
Fair value warrant \| £					£ 1,273	£ 7,923	£ 0
Variance recorded \| £					£ 6,650	£ 1,068	£ 0
Warrants
Disclosure of classes of share capital [line items]
Exercise price (pounds per share) \| £ / shares				£ 1.7238	£ 1.7238	£ 1.7238
Number of shares subscribed from warrant maximum (in shares) \| shares				12,446,370	12,401,262	12,446,370
Transaction costs allocated to the issue of warrants (note 19) \| £				£ 600
Warrants forfeited (in shares) \| shares					45,108	0
Ordinary shares
Disclosure of classes of share capital [line items]
Transaction costs allocated to the issue of warrants (note 19) \| £				£ 2,300

Warrants - Assumptions in applying the Black-Scholes model, fair value warrants (Details) - £ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 13, 2017	Jul. 29, 2016
Disclosure of classes of share capital [line items]
Warrants (in shares)	622,318,538
Exercise price (pounds per share)			£ 1.10
Warrants
Disclosure of classes of share capital [line items]
Warrants (in shares)	12,401,262	12,446,370		12,446,370
Exercise price (pounds per share)	£ 1.7238	£ 1.7238		£ 1.7238
Risk-free interest rate	0.42%	0.088%
Expected term to exercise	1 year 9 months 15 days	2 years 5 months 5 days
Annualized volatility	47.35%	73.53%
Dividend rate	0.00%	0.00%

Warrants - Fair value adjustments (Details) - GBP (£) £ in Thousands		12 Months Ended
	Jul. 29, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation Of Changes in Warrants Outstanding [Roll Forward]
Beginning balance		£ 7,923	£ 0
On issuance of shares	£ 9,000	0	8,991
Fair value adjustments recognized in profit or loss		(6,650)	(1,068)	£ 0
Ending balance		£ 1,273	£ 7,923	£ 0

Warrants - Effect when underlying parameters deviate (Details) - GBP (£) £ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of share capital, reserves and other equity interest [Abstract]
Variable up, Volatility (up / down 10% pts)	£ 1,921
Base case, Volatility (up / down 10% pts)	1,273	£ 7,923	£ 0
Variable down, Volatility (up / down 10% pts)	694
Variable up, Time to maturity (up / down 6 months)	1,677
Variable down, Time to maturity (up / down 6 months)	£ 843
Volatility (up/down), percentage	10.00%
Time to maturity (up, down), months	6 months

Financial commitments (Details) - Land and Buildings - GBP (£) £ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Operating lease obligations:
Minimum lease payments payable under non-cancellable operating lease	£ 568	£ 270
Within one year
Operating lease obligations:
Minimum lease payments payable under non-cancellable operating lease	291	270
Between one and five years
Operating lease obligations:
Minimum lease payments payable under non-cancellable operating lease	£ 277	£ 0

Related parties transactions and other shareholder matters (Details)	12 Months Ended
	Dec. 31, 2017
Vivo Capital, OrbiMed And Abingworth \| Entities with joint control or significant influence over entity
Disclosure of transactions between related parties [line items]
Percent of issued ordinary shares	6.50%

Segmental reporting	12 Months Ended
Segmental reporting	Dec. 31, 2017
Disclosure of entity's operating segments [Abstract]
Segmental reporting	Segmental reporting The Company’s activities are covered by one operating and reporting segment: Drug Development. There have been no changes to management’s assessment of the operating and reporting segment of the Company during the period. All non-current assets are based in the United Kingdom.

Segmental reporting (Details)	12 Months Ended
Segmental reporting (Details)	Dec. 31, 2017 segment
Disclosure of entity's operating segments [Abstract]
Number of operating and reportable segments	1

Earnings per share	12 Months Ended
Earnings per share	Dec. 31, 2017
Disclosure of earnings per share [Abstract]
Earnings per share	Earnings per share Basic loss per ordinary share of 23.4p (2016: 15.0p and 2015: 37.1p) for the Company is calculated by dividing the loss for the year ended December 31, 2017 by the weighted average number of ordinary shares in issue of 87,748,031 as of December 31, 2017 (2016: 33,499,413 and 2015: 20,198,469). Potential ordinary shares are not treated as dilutive as the entity is loss making and such shares would be anti-dilutive.