v3.25.4
Derivative financial instruments - Disclosure of hedging instruments which are carried on the Group's balance sheet, cash flow and net investment hedging (Details) - Fair value hedges - GBP (£)
£ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 108,093 103,822
Change in fair value used as a basis to determine ineffectiveness £ 736 £ 593
Interest rate risk    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 95,612 89,602
Change in fair value used as a basis to determine ineffectiveness £ 710 £ (38)
Inflation risk    
Disclosure of detailed information about hedging instruments [line items]    
Nominal amount 12,481 14,220
Change in fair value used as a basis to determine ineffectiveness £ 26 £ 631
Derivative financial instruments    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 75 147
Hedging instrument, liabilities (517) (322)
Derivative financial instruments | Interest rate risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 2 26
Hedging instrument, liabilities (3) (16)
Derivative financial instruments | Inflation risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, assets 73 121
Hedging instrument, liabilities (514) (306)
Loan liabilities    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities 0 0
Loan liabilities | Interest rate risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities 0 0
Loan liabilities | Inflation risk    
Disclosure of detailed information about hedging instruments [line items]    
Hedging instrument, liabilities £ 0 £ 0