Tax - Analysis of deferred tax (Details) - GBP (£) £ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deferred tax
Deferred tax asset	£ 1,876	£ 1,894
Deferred tax liability	(99)	(141)
Net deferred tax asset	£ 1,777	£ 1,753	£ 1,951

The amounts of income taxes recoverable in future periods in respect of: (a) deductible temporary differences; (b) the carryforward of unused tax losses; and (c) the carryforward of unused tax credits. [Refer: Temporary differences [member]; Unused tax credits [member]; Unused tax losses [member]]

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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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant