v3.26.1
Pensions and other post-retirement benefits - Disclosure of amounts recognised in the income statement and statement of other comprehensive income (Details) - GBP (£)
£ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Included within operating costs      
Administration costs £ 27 £ 22 £ 22
Defined benefit plan costs:      
Current service cost 123 138 143
Past service cost – redundancies 2 1 9
Gains on settlement (25) 0 (30)
Post-employment benefit expense, payroll cost, defined benefit plans 100 139 122
Included within finance income and costs      
Net interest income adjusted for change to irrecoverable surplus (114) (98) (100)
Total (income)/expense included in income statement 13 63 44
Exchange losses (14) (20) (6)
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations 287 (29) (218)
Adjustments for restrictions on the defined benefit asset (155) (77) 0
Total (loss)/gain included in the statement of other comprehensive income 118 (126) (224)
Property, plant and equipment      
Defined benefit plan costs:      
Current service cost 33 34 35
Pensions | UK      
Included within operating costs      
Administration costs 19 14 13
Defined benefit plan costs:      
Current service cost 34 45 45
Past service cost – redundancies 2 1 9
Gains on settlement 0 0 0
Post-employment benefit expense, payroll cost, defined benefit plans 36 46 54
Included within finance income and costs      
Net interest income adjusted for change to irrecoverable surplus (58) (68) (84)
Total (income)/expense included in income statement (3) (8) (17)
Exchange losses 0 0 0
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations (156) (257) (474)
Adjustments for restrictions on the defined benefit asset 0 0 0
Total (loss)/gain included in the statement of other comprehensive income (156) (257) (474)
Pensions | US      
Included within operating costs      
Administration costs 6 6 7
Defined benefit plan costs:      
Current service cost 62 68 72
Past service cost – redundancies 0 0 0
Gains on settlement (25) 0 (30)
Post-employment benefit expense, payroll cost, defined benefit plans 37 68 42
Included within finance income and costs      
Net interest income adjusted for change to irrecoverable surplus (22) (19) (13)
Total (income)/expense included in income statement 21 55 36
Exchange losses (7) (10) (5)
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations (54) 106 99
Adjustments for restrictions on the defined benefit asset 0 0 0
Total (loss)/gain included in the statement of other comprehensive income (61) 96 94
Other post-retirement benefits | US      
Included within operating costs      
Administration costs 2 2 2
Defined benefit plan costs:      
Current service cost 27 25 26
Past service cost – redundancies 0 0 0
Gains on settlement 0 0 0
Post-employment benefit expense, payroll cost, defined benefit plans 27 25 26
Included within finance income and costs      
Net interest income adjusted for change to irrecoverable surplus (34) (11) (3)
Total (income)/expense included in income statement (5) 16 25
Exchange losses (7) (10) (1)
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations 497 122 157
Adjustments for restrictions on the defined benefit asset (155) (77) 0
Total (loss)/gain included in the statement of other comprehensive income £ 335 £ 35 £ 156