Condensed Consolidated Statements of Shareholders’ Equity $ in Thousands	USD ($) shares	ADDITIONAL PAID-IN CAPITAL USD ($)	ACCUMULATED OTHER COMPREHENSIVE (LOSS)/ INCOME USD ($)	ACCUMULATED DEFICIT USD ($)	Ordinary shares £ / shares shares	Ordinary shares COMMON STOCK USD ($) shares	Deferred shares £ / shares shares	Deferred shares COMMON STOCK USD ($) shares
Beginning balance (in shares) at Dec. 31, 2021 | shares						42,019,874,000		1,000
Beginning balance at Dec. 31, 2021	$ 284,412	$ 444,750	$ 8,840	$ (169,641)		$ 435		$ 28
Exercise of share options (in shares) | shares					376,158	376,158,000
Exercise of share options	397	393				$ 4
Vesting of restricted stock units (in shares) | shares					10,659	68,534,000
Vesting of restricted stock units	1					$ 1
Share-based compensation expense	3,128	3,128
Unrealized loss on foreign currency translation	(7,193)		(7,193)
Net loss	(21,171)			(21,171)
Ending balance (in shares) at Mar. 31, 2022 | shares						42,464,566,000		1,000
Ending balance at Mar. 31, 2022	259,574	448,271	1,647	(190,812)		$ 440		$ 28
Common stock, par value (in GBP per share) | £ / shares					£ 0.008		£ 21,921.504
Beginning balance (in shares) at Dec. 31, 2022 | shares					42,631,794	42,631,794,000	1	1,000
Beginning balance at Dec. 31, 2022	$ 181,280	458,825	(16,867)	(261,146)		$ 440		$ 28
Exercise of share options (in shares) | shares	3,790				3,790	3,790,000
Issuance of ordinary shares under ATM offering, net of issuance costs (in shares) | shares						113,420,000
Issuance of ordinary shares under ATM facility, net of issuance costs	$ 1,188	1,187				$ 1
Shares tendered for withholding taxes	(109)	(109)
Vesting of restricted stock units (in shares) | shares					21,579	30,481,000
Vesting of restricted stock units	0	(1)				$ 1
Share-based compensation expense	4,071	4,071
Unrealized loss on foreign currency translation	(578)		(578)
Net loss	(24,208)			(24,208)
Ending balance (in shares) at Mar. 31, 2023 | shares					42,779,485	42,779,485,000	1	1,000
Ending balance at Mar. 31, 2023	$ 161,644	$ 463,973	$ (17,445)	$ (285,354)		$ 442		$ 28
Common stock, par value (in GBP per share) | £ / shares					£ 0.008		£ 21,921.504