v3.25.3
Segmental analysis - Schedule of operating profit/(loss) by segment (Details) - GBP (£)
£ in Millions
 6 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Disclosure of operating segments [line items]    
Operating profit from continuing operations £ 1,526 £ 1,309
Share of post-tax results of joint ventures and associates 39 57
Finance income 208 234
Finance costs (947) (916)
Profit before tax 826 684
UK    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 1,498 1,294
US    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 28 15
Operating segments | UK Electricity Transmission    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 810 642
Operating segments | UK Electricity Distribution    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 488 759
Operating segments | UK Electricity System Operator    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 0 (213)
Operating segments | New England    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 61 87
Operating segments | New York    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 78 (50)
Operating segments | National Grid Ventures    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 126 145
Operating segments | Other    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (37) (61)
Total operating profit/(loss) before exceptional items and remeasurements    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 1,615 1,210
Share of post-tax results of joint ventures and associates 39 60
Finance income 206 231
Finance costs (884) (901)
Profit before tax 976 600
Total operating profit/(loss) before exceptional items and remeasurements | UK    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 1,476 1,173
Total operating profit/(loss) before exceptional items and remeasurements | US    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 139 37
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | UK Electricity Transmission    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 813 642
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | UK Electricity Distribution    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 488 764
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | UK Electricity System Operator    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 0 (364)
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | New England    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 81 89
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | New York    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 73 (30)
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | National Grid Ventures    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 187 147
Total operating profit/(loss) before exceptional items and remeasurements | Operating segments | Other    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (27) (38)
Exceptional items and remeasurements    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (89) 99
Share of post-tax results of joint ventures and associates 0 (3)
Finance income 2 3
Finance costs (63) (15)
Profit before tax (150) 84
Exceptional items and remeasurements | UK    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 22 121
Exceptional items and remeasurements | US    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (111) (22)
Exceptional items and remeasurements | Operating segments | UK Electricity Transmission    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (3) 0
Exceptional items and remeasurements | Operating segments | UK Electricity Distribution    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 0 (5)
Exceptional items and remeasurements | Operating segments | UK Electricity System Operator    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 0 151
Exceptional items and remeasurements | Operating segments | New England    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (20) (2)
Exceptional items and remeasurements | Operating segments | New York    
Disclosure of operating segments [line items]    
Operating profit from continuing operations 5 (20)
Exceptional items and remeasurements | Operating segments | National Grid Ventures    
Disclosure of operating segments [line items]    
Operating profit from continuing operations (61) (2)
Exceptional items and remeasurements | Operating segments | Other    
Disclosure of operating segments [line items]    
Operating profit from continuing operations £ (10) £ (23)