Liquidity risk- Narrative (Details) - GBP (£) £ in Millions	Dec. 31, 2024	Dec. 31, 2023
Liquidity risk [Abstract]
Undated subordinated liabilities	£ 16	£ 16

The amount of subordinated liabilities that do not have a specified repayment date. [Refer: Subordinated liabilities]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2024-03-27

Name:	ifrs-full_UndatedSubordinatedLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant