Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Summary of Loss Before Provision for Income Taxes

Loss before provision for income taxes consisted of the following (in thousands):

	December 31,
	2022			2021			2020
United Kingdom	$	(71,405	)	$	(61,182	)	$	(33,204	)
Foreign		340			120			8
	$	(71,065	)	$	(61,062	)	$	(33,196	)

Summary of Income Tax Provision

The income tax provision for the years ended December 31, 2022, 2021 and 2020 is comprised of the following (in thousands):

	December 31,
	2022			2021			2020
Current expense:
United Kingdom	$	—		$	—		$	—
Foreign		337			59			7
Total current expense:		337			59			7
Deferred expense (benefit):
United Kingdom		—			—			—
Foreign		(226	)		(22	)		(4	)
Total deferred expense (benefit):		(226	)		(22	)		(4	)
Total income tax expense:	$	111		$	37		$	3

Schedule of Reconciliation of Income Tax Expense Computed at Statutory UK Income Taxes

A reconciliation of income tax expense computed at the statutory UK income tax rate to income taxes as reflected in the consolidated financial statements is as follows:

	Year Ended December 31,
	2022			2021			2020
Income taxes at UK statutory rate		19.00	%		19.00	%		19.00	%
Return to provision		6.87	%		—			—
R&D expenditure		(8.30	)%		(6.67	)%		(6.69	)%
Change in valuation allowance		(23.58	)%		(20.12	)%		(13.12	)%
Change in UK tax rate		5.66	%		7.64	%		—
Other		0.19	%		(0.13	)%		0.80	%
		(0.16	)%		(0.28	)%		(0.01	)%

Summary of Significant Component of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2022, 2021 and 2020 consist of the following (in thousands):

	December 31,
	2022			2021					2020
Deferred tax assets
Net operating loss carryforwards	$	35,121		$	17,742				$	7,065
Depreciation		(7,989	)		(1,311	)				(983	)
Non-cash share-based compensation		4,456			2,328					769
Other		2,143			329					241
Total deferred tax assets	$	33,731		$	19,088		$	—	$	7,092
Valuation allowance		(33,480	)	$	(19,062	)			$	(7,088	)
Net deferred tax assets	$	251		$	26				$	4

Summary of Changes in Valuation Allowance for Deferred Tax Assets

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2022, 2021 and 2020 related primarily to the increases in net operating loss carryforwards and research and development tax credit carryforwards were as follows (in thousands):

	December 31,
	2022			2021			2020
Valuation allowance at beginning of year	$	19,062		$	7,088		$	2,391
Increases recorded to income tax provision		12,731			7,624			4,628
Exchange difference		(2,332	)		(313	)		69
Change in tax rate		4,019			4,663			—
Valuation allowance at end of year	$	33,480		$	19,062		$	7,088