Segmental analysis - Schedule of geographical analysis of non-current assets (Details) - GBP (£) £ in Millions |
Sep. 30, 2026 |
Mar. 31, 2026 |
|---|---|---|
| Disclosure of operating segments [line items] | ||
| Non-current assets other than financial instruments, deferred tax assets, post-employment benefit assets, and rights arising under insurance contracts | £ 102,151 | £ 96,824 |
| Pension assets | 2,617 | 2,507 |
| Financial and other investments | 1,898 | 842 |
| Derivative financial assets | 558 | 623 |
| Total non-current assets | 107,224 | 100,796 |
| UK | ||
| Disclosure of operating segments [line items] | ||
| Non-current assets other than financial instruments, deferred tax assets, post-employment benefit assets, and rights arising under insurance contracts | 50,781 | 47,551 |
| US | ||
| Disclosure of operating segments [line items] | ||
| Non-current assets other than financial instruments, deferred tax assets, post-employment benefit assets, and rights arising under insurance contracts | £ 51,370 | £ 49,273 |