v3.25.4
Financial Risk Management - Schedule of Contractual Undiscounted Cash Flows Analysed by Maturity and Currency (Detail) - GBP (£)
£ in Millions
Dec. 31, 2025
Dec. 31, 2024
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds £ 935 £ 955 [1]
Rate derivatives - inflows (82) (414)
Rate derivatives - outflows 67 412
FX forwards - inflows (326) (1,034)
FX forwards - outflows 324 1,049
Total 918 968
US Dollars [member]    
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds 0 0 [1]
Rate derivatives - inflows 0 (2)
Rate derivatives - outflows 0 176
FX forwards - inflows 0 0
FX forwards - outflows 324 1,049
Total 324 1,223
Sterling [member]    
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds 935 705 [1]
Rate derivatives - inflows (82) (163)
Rate derivatives - outflows 67 235
FX forwards - inflows (326) (1,034)
FX forwards - outflows 0 0
Total 594 (257)
Other currency [member]    
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds 0 250 [1]
Rate derivatives - inflows 0 (249)
Rate derivatives - outflows 0 1
FX forwards - inflows 0 0
FX forwards - outflows 0 0
Total 0 2
In less than one year [member]    
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds 32 250 [1]
Rate derivatives - inflows (11) (394)
Rate derivatives - outflows 9 408
FX forwards - inflows (326) (1,034)
FX forwards - outflows 324 1,049
Total 28 279
One to five years [member]    
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds 478 0 [1]
Rate derivatives - inflows (39) (3)
Rate derivatives - outflows 32 1
FX forwards - inflows 0 0
FX forwards - outflows 0 0
Total 471 (2)
Later than five years [member]    
Disclosure of undiscounted cash flows financial assets liabilities [line items]    
Bonds 425 705 [1]
Rate derivatives - inflows (32) (17)
Rate derivatives - outflows 26 3
FX forwards - inflows 0 0
FX forwards - outflows 0 0
Total £ 419 £ 691
[1] The 2024 figures for bonds have been given on a discounted basis for the year ended 31 December 2025. If the same methodology had been applied for the year ended 31 December 2024, the total value of the bonds would be £1,219m, of which £284m is greater than one month and less than one year, £128m later than one year but less than five years, and £807m greater than five years. The currency split is sterling £967m and Euro £252m.