Ordinary shares (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2022 item $ / shares £ / shares shares	Dec. 31, 2021 $ / shares £ / shares shares
Ordinary shares
Vote per ordinary share | item	1
Dividends declared | $ / shares	$ 0	$ 0
Ordinary shares, shares authorized | shares	57,820,181	55,295,420
Ordinary shares, nominal value | £ / shares	$ 0.01	$ 0.01