Income Tax - Components of loss before income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
United Kingdom	$ (46,868)	$ (72,244)
United States	(31,914)	(16,358)
Loss before income tax	$ (78,782)	$ (88,602)