Warrant liability (Tables)

12 Months Ended

Dec. 31, 2019

Warrant liability

Summary of roll-forward of the fair values of the Company’s warrant liability

The following table provides a roll-forward of the fair values of the Company’s warrant liability for which fair value was determined by Level 3 inputs (in thousands):

	Warrant
	Liability
Fair value at December 31, 2018	$	4,804
Change in fair value of warrant liability recorded as other expense		5,381
Conversion of warrant liability to equity upon closing of IPO and exercise of warrants		(10,021)
Impact of exchange rates on translation of warrant liability to USD included in accumulated other comprehensive income (loss)		(164)
Fair value at December 31, 2019	$	—

Warrants

Warrant liability

Summary of unobservable inputs to the fair value measurement of the warrant liability

		Remeasurement upon closing
	of the IPO on May 28, 2019						December 31, 2018
	Series A			Series B1			Series A			Series B1
	Warrants			Warrants			Warrants			Warrants (1)
Risk-free rate		2.2	%		2.1	%		2.6	%		2.5	%
Expected dividend yield		—	%		—	%		—	%		—	%
Expected term (years)		8.0			5.8			8.4			6.25
Expected volatility		74.7	%		78.2	%		75.4	%		79.6	%
Exercise price	£	0.01		£	0.01		£	0.01		£	0.01
Fair value of preferred shares or ordinary shares underlying the warrant	$	12.28		$	12.28		$	8.61		$	4.15

⁽¹⁾ The fair value of the Series B1 preferred shares underlying the warrants to purchase Series B1 preferred shares at December 31, 2018 includes a 50% probability that the warrants will be not be exercisable prior to the IPO, based on their contractual terms.