Disposals and other non-operating items - Summary of disposals and other non-operating item (Detail) - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disposals and other non-operating items
Revaluation of investments	£ 12	£ (2)	£ (11)
Loss on disposal of businesses	(3)	(4)	(61)
Net loss on disposals and other non-operating items	£ 9	£ (6)	£ (72)

The gains (losses) on financial assets at fair value through profit or loss. [Refer: Financial assets at fair value through profit or loss]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
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-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 56
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-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_56_a_i&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
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