v3.26.1
Net debt - Schedule of changes in net debt (Details) - GBP (£)
£ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Liabilities from financing activities      
Liabilities arising from financing activities at start of year £ (48,272) £ (47,836) £ (43,778)
Proceeds received from loans (4,172) (3,237) (5,563)
Repayment of loans 2,961 2,861 1,701
Payments of lease liabilities 145 130 118
Net movements in short-term borrowings 2,225 (925) (544)
Cash inflows on derivatives (93) (62) (86)
Cash outflows on derivatives 38 106 58
Interest paid 1,932 1,920 1,627
Non-net debt financing cash flows (33) (8) (18)
Fair value gains and losses 667 (56) (29)
Foreign exchange movements (190) 866 718
Interest (charges)/income (1,952) (1,958) (1,848)
Other non-cash movements (223) (207) (205)
Reclassification to held for sale   134 13
Liabilities arising from financing activities at end of year (46,967) (48,272) (47,836)
Cash and cash equivalents      
Cash and cash equivalents at start of year 1,178 559 163
Net increase (decrease) in cash and cash equivalents (948) 765 427
Foreign exchange movements (8) (23) (1)
Reclassification to held for sale 153 (123) (30)
Cash and cash equivalents at end of year 375 1,178 559
Financial investments      
Financial investments at start of year 5,753 3,699 2,605
Net movements in short-term financial investments (3,285) 2,606 1,141
Interest received (231) (332) (148)
Fair value gains and losses 5 1 4
Foreign exchange movements (17) (25) (49)
Interest (charges)/income 230 338 152
Reclassification to held for sale (2) (534) (6)
Financial investments at end of year 2,453 5,753 3,699
Other financing derivatives      
Other financing derivatives at start of year (30) (29) 37
Cash inflows on derivatives (20) (11) (123)
Cash outflows on derivatives 6 6 0
Derivative cash flows included in capital expenditure 5 9 5
Derivative cash flows included in revenue 1 (8) (11)
Fair value gains and losses   (7) 60
Interest (charges)/income 17 10 7
Other non-cash movements     (4)
Other financing derivatives at end of year (21) (30) (29)
Net debt      
Net debt at start of year (41,371) (43,607) (40,973)
Net increase (decrease) in cash and cash equivalents (948) 765 427
Proceeds received from loans (4,172) (3,237) (5,563)
Repayment of loans 2,961 2,861 1,701
Payments of lease liabilities 145 130 118
Net movements in short-term borrowings 2,225 (925) (544)
Cash inflows on derivatives (93) (62) (86)
Cash outflows on derivatives 38 106 58
Interest paid 1,932 1,920 1,627
Non-net debt financing cash flows (33) (8) (18)
Net movements in short-term financial investments (3,285) 2,606 1,141
Cash inflows on derivatives (20) (11) (123)
Cash outflows on derivatives 6 6 0
Derivative cash flows included in capital expenditure 5 9 5
Interest received (231) (332) (148)
Derivative cash flows included in revenue 1    
Fair value gains and losses 672 (62) 35
Foreign exchange movements (215) 818 668
Interest (charges)/income (1,705) (1,610) (1,689)
Other non-cash movements (223) (207) (209)
Reclassification to held for sale 151 (523) (23)
Net debt at end of year (44,160) (41,371) (43,607)
Interest payable 459 477 490
Borrowings      
Liabilities from financing activities      
Liabilities arising from financing activities at start of year (47,539) (47,072) (42,985)
Proceeds received from loans (4,172) (3,237) (5,563)
Repayment of loans 2,961 2,861 1,701
Payments of lease liabilities 145 130 118
Net movements in short-term borrowings 2,225 (925) (544)
Interest paid 1,659 1,608 1,330
Non-net debt financing cash flows (33) (8) (18)
Fair value gains and losses 118 (26) (69)
Foreign exchange movements (190) 866 718
Interest (charges)/income (1,706) (1,663) (1,564)
Other non-cash movements (223) (207) (209)
Reclassification to held for sale   134 13
Liabilities arising from financing activities at end of year (46,755) (47,539) (47,072)
Net debt      
Proceeds received from loans (4,172) (3,237) (5,563)
Repayment of loans 2,961 2,861 1,701
Payments of lease liabilities 145 130 118
Net movements in short-term borrowings 2,225 (925) (544)
Interest paid 1,659 1,608 1,330
Non-net debt financing cash flows (33) (8) (18)
Financing derivatives used to hedge debt      
Liabilities from financing activities      
Liabilities arising from financing activities at start of year (733) (764) (793)
Cash inflows on derivatives (93) (62) (86)
Cash outflows on derivatives 38 106 58
Interest paid 273 312 297
Fair value gains and losses 549 (30) 40
Interest (charges)/income (246) (295) (284)
Other non-cash movements     4
Liabilities arising from financing activities at end of year (212) (733) (764)
Net debt      
Cash inflows on derivatives (93) (62) (86)
Cash outflows on derivatives 38 106 58
Interest paid 273 £ 312 £ 297
Non-current assets      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year 587    
Other financing derivatives      
Other financing derivatives at end of year 7    
Net debt      
Net debt at end of year 594    
Non-current assets | Financing derivatives used to hedge debt      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year 587    
Current assets      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year 77    
Cash and cash equivalents      
Cash and cash equivalents at end of year 375    
Financial investments      
Financial investments at end of year 2,453    
Other financing derivatives      
Other financing derivatives at end of year 46    
Net debt      
Net debt at end of year 2,951    
Current assets | Financing derivatives used to hedge debt      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year 77    
Current liabilities      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year (4,091)    
Other financing derivatives      
Other financing derivatives at end of year (46)    
Net debt      
Net debt at end of year (4,137)    
Current liabilities | Borrowings      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year (3,900)    
Current liabilities | Financing derivatives used to hedge debt      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year (191)    
Non-current liabilities      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year (43,540)    
Other financing derivatives      
Other financing derivatives at end of year (28)    
Net debt      
Net debt at end of year (43,568)    
Non-current liabilities | Borrowings      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year (42,855)    
Non-current liabilities | Financing derivatives used to hedge debt      
Liabilities from financing activities      
Liabilities arising from financing activities at end of year £ (685)