Subsidiary undertakings, joint ventures and associates - Disclosure of interests in joint operations (Details) |
12 Months Ended |
|---|---|
|
Mar. 31, 2024
£ / shares
shares
| |
| Disclosure of joint operations [line items] | |
| Par value per share (EUR/GBP per share) | £ 0.1243129 |
| Eastern Green Link 1 Limited | |
| Disclosure of joint operations [line items] | |
| Proportion of ownership interest in joint operation | 50.00% |
| Eastern Green Link 2 Limited | |
| Disclosure of joint operations [line items] | |
| Proportion of ownership interest in joint operation | 50.00% |
| NGET/SPT Upgrades Limited | |
| Disclosure of joint operations [line items] | |
| Proportion of ownership interest in joint operation | 50.00% |
| National Grid Electricity Transmission plc | A Ordinary shares | NGET/SPT Upgrades Limited | |
| Disclosure of joint operations [line items] | |
| Number of shares held in joint operation (in shares) | shares | 50 |
| Par value per share (EUR/GBP per share) | £ 1.00 |