Provisions for liabilities and charges - Additional Information (Details) - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disclosure of other provisions [abstract]
Legal proceedings provision	£ 132	£ 35
Charged to the income statement	129	90
Legal provision charges/(gains)	68	£ (11)	£ 0
Expected provision to be settled in less than one year	123
Expected provision to be settled in more than one year	£ 9

The amount of provision for legal proceedings. [Refer: Other provisions]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 37
-IssueDate 2024-01-01
-Section Example 10 A court case
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=37&code=ifrs-tx-2024-en-r&doctype=Illustrative%20Examples&dita_xref=IAS37_IE_C_ex10_TI
-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 37
-IssueDate 2024-01-01
-Paragraph 87
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=37&code=ifrs-tx-2024-en-r&anchor=para_87&doctype=Standard
-URIDate 2024-03-27

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