Dividends - Narrative (Details) £ / shares in Units, £ in Millions	12 Months Ended
Mar. 31, 2026 GBP (£) £ / shares
Dividend [Abstract]
Dividends declared before financial statements authorised for issue (GBP per share) \| £ / shares	£ 0.3214
Dividends declared before financial statements authorised for issue \| £	£ 1,598

The amount of dividends proposed or declared after the reporting period but before financial statements are authorised for issue. Such dividends are not recognised as a liability at the end of the reporting period because no obligation exists at that time.

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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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Name:	ifrs-full_DividendsProposedOrDeclaredBeforeFinancialStatementsAuthorisedForIssueButNotRecognisedAsDistributionToOwners
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration