Significant accounting policies - Going concern (Details) - GBP (£) £ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Significant accounting policies
Cash and cash equivalents	£ 89,693	£ 62,927	£ 157,552	£ 212,660
Expected funding requirements over next 12-month period	£ 80,000

The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant