Exchange rates (Details)	12 Months Ended
Dec. 31, 2023 € / £	Dec. 31, 2023 € / £ $ / £	Dec. 31, 2022 € / £	Dec. 31, 2022 € / £ $ / £	Dec. 31, 2021 € / £	Dec. 31, 2021 $ / £	Dec. 31, 2023 $ / £	Dec. 31, 2022 $ / £
Exchange rates
Average foreign exchange rate	1.15	1.24	1.17	1.24	1.16	1.38
Closing foreign exchange rate	1.15	1.15	1.13	1.13			1.28	1.21

The spot exchange rate at the end of the reporting period. Exchange rate is the ratio of exchange for two currencies. Spot exchange rate is the exchange rate for immediate delivery.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2023-03-23

Name:	ifrs-full_ClosingForeignExchangeRate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant