Ordinary shares (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2023 Vote $ / shares £ / shares shares	Dec. 31, 2022 £ / shares $ / shares shares
Ordinary shares.
Vote per ordinary share | Vote	1
Dividends declared | $ / shares	$ 0	$ 0
Ordinary shares, shares authorized | shares	59,612,613	57,820,181
Ordinary shares, nominal value | £ / shares	$ 0.01	$ 0.01