v3.25.4
Derivative financial instruments - Disclosure of hedging instruments which are carried on the Group's balance sheet, fair value hedging (Details) - GBP (£)
£ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Cash flow    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 127,147 113,323
Change in fair value used as a basis to determine ineffectiveness £ 2,642 £ (1,350)
Cash flow | Interest rate risk    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 94,727 80,382
Change in fair value used as a basis to determine ineffectiveness £ 876 £ (919)
Cash flow | Foreign exchange risk    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 26,048 26,564
Change in fair value used as a basis to determine ineffectiveness £ 1,645 £ (313)
Cash flow | Inflation risk    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 6,372 6,377
Change in fair value used as a basis to determine ineffectiveness £ 121 £ (118)
Net investment | Foreign exchange risk    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 10,428 11,601
Change in fair value used as a basis to determine ineffectiveness £ 499 £ (10)
Derivative financial instruments | Cash flow    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 1,677 611
Hedging instrument, liabilities (39) (307)
Derivative financial instruments | Cash flow | Interest rate risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 0 0
Hedging instrument, liabilities 0 0
Derivative financial instruments | Cash flow | Foreign exchange risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 1,677 611
Hedging instrument, liabilities (39) (307)
Derivative financial instruments | Cash flow | Inflation risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 0 0
Hedging instrument, liabilities 0 0
Derivative financial instruments | Net investment | Foreign exchange risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 155 36
Hedging instrument, liabilities (43) (66)
Loan liabilities | Cash flow    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities 0 0
Loan liabilities | Cash flow | Interest rate risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities 0 0
Loan liabilities | Cash flow | Foreign exchange risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities 0 0
Loan liabilities | Cash flow | Inflation risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities 0 0
Loan liabilities | Net investment | Foreign exchange risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities £ (6,109) £ (7,588)