v3.25.3
Pensions and other post-retirement benefit obligations - Schedule of defined benefit plan recognised in balance sheet (Details) - GBP (£)
£ in Millions
Sep. 30, 2025
Mar. 31, 2025
Sep. 30, 2024
Mar. 31, 2024
Disclosure of defined benefit plans [line items]        
Other post-employment liabilities £ (44) £ (47)    
Net defined benefit liability (asset) including restrictions on assets recognized 2,296 1,993    
Restrictions on asset recognised (221) (77)    
Net defined benefit asset 2,075 1,916 £ 1,875 £ 1,814
Assets 2,424 2,489    
Liabilities (349) (573)    
Funded obligations        
Disclosure of defined benefit plans [line items]        
Present value of obligations (15,628) (16,154)    
Fair value of plan assets 18,218 18,441    
Funding surplus/(deficit) 2,590 2,287    
Unfunded obligations        
Disclosure of defined benefit plans [line items]        
Present value of obligations £ (250) £ (247)