v3.25.4
Classification of Financial Instruments -Schedule of Analysis of the Movement in the Fair Value of the Deferred and Contingent Consideration (Detail) - GBP (£)
£ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of fair value measurement of liabilities [line items]    
At 1 January £ (1,788)  
At 31 December (1,761) £ (1,788)
Contingent consideration [member]    
Disclosure of fair value measurement of liabilities [line items]    
At 1 January (1)  
Exchange differences 0  
Acquisitions 0  
Fair value movements – Income statement 0  
Repayments 0  
At 31 December (1) (1)
Deferred Consideration [member]    
Disclosure of fair value measurement of liabilities [line items]    
At 1 January (21)  
Exchange differences 1  
Acquisitions 0  
Fair value movements – Income statement 0  
Repayments 4  
At 31 December (16) (21)
Deferred And Contingent Consideration [Member]    
Disclosure of fair value measurement of liabilities [line items]    
At 1 January (22) (57)
Exchange differences 1 0
Acquisitions 0 (1)
Fair value movements – Income statement 0 (2)
Repayments 4 38
At 31 December £ (17) £ (22)