Share capital - Narrative (Details) - GBP (£) £ / shares in Units, £ in Millions |
12 Months Ended | |
|---|---|---|
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Disclosure of classes of share capital [abstract] | ||
| Par value per share (GBP per share) | £ 0.1243129 | |
| Number of ordinary shares per ADS (in shares) | 5 | |
| Proceeds from issuing shares | £ 2 | £ 5 |
| Amount of unclaimed dividends derecognised | £ 5 | £ 5 |
| Treasury stock (in shares) | 247,000,000 | 254,000,000 |
| Treasury shares, market value | £ 2,637 | £ 2,783 |
| Treasury shares, gifted (in shares) | 4,000,000 | 3,000,000 |
| Treasury stock, reissued (in shares) | 3,000,000 | 2,000,000 |
| Shares reissued to employee share schemes as percent of ordinary shares | 0.20% | 0.10% |
| Treasury shares, reissued, nominal value | £ 1 | £ 1 |
| Gross proceeds from reissue of treasury shares | 21 | 16 |
| Purchase of own shares, employee share trusts | £ 6 | £ 4 |
| Maximum number of treasury shares held during the year (in shares) | 254,000,000 | 259,000,000 |
| Treasury shares as percent of ordinary shares | 6.40% | 6.60% |
| Treasury shares, nominal value | £ 32 | £ 32 |