Revenue and the results of the business are analysed by operating segment, based on the information the Board of Directors uses internally for the purposes of evaluating the performance of each operating segment and determining resource allocation between them. The Board is National Grid’s chief operating decision maker (as defined by IFRS 8 ‘Operating Segments’) and as a matter of course, the Board considers multiple profitability measures by segment, being ‘adjusted profit’ and ‘underlying profit’. Adjusted profit excludes exceptional items and remeasurements (as defined in note 4) and is used by management and the Board to monitor financial performance as it is considered that it aids the comparability of our reported financial performance from year to year. Underlying profit, as presented in the Annual Report and Accounts, represents adjusted profit and also excludes the effects of timing, major storm costs and deferred tax expenses in our UK Electricity Transmission and UK Electricity Distribution businesses. The measure of profit disclosed in this note and the primary profitability benchmark considered by the chief operating decision maker is adjusted profit, as this is the measure that is most consistent with the IFRS results reported within these financial statements.

The results of our five principal businesses are reported to the Board and are accordingly treated as reportable operating segments. All other operating segments are reported to the Board on an aggregated basis. The following table describes the main activities for each reportable operating segment:


UK Electricity Transmission			The high-voltage electricity transmission networks in England and Wales. This includes our Accelerated Strategic Transmission Investment projects to connect more clean, low-carbon power to the transmission network in England and Wales.
UK Electricity Distribution			The electricity distribution networks of NGED in the East Midlands, West Midlands and South West of England and South Wales.
New England			Electricity distribution networks, high-voltage electricity transmission networks and gas distribution networks in New England.
New York			Electricity distribution networks, high-voltage electricity transmission networks and gas distribution networks in New York.
National Grid Ventures			Comprises our electricity interconnectors in the UK, our electricity generation business in the US and all commercial operations in LNG at Providence, Rhode Island in the US. While NGV operates outside our regulated core business, the electricity interconnectors in the UK are subject to indirect regulation by Ofgem regarding the level of returns they can earn. During the prior year, the Group sold its interest in NG Renewables and Grain LNG.

The New England and New York segments typically experience seasonal fluctuations in revenue and operating profit due to higher delivery volumes during the second half of the financial year, for example as a result of colder weather over the winter months driving increased heating demand. These seasonal fluctuations have a consequential impact on the working capital balances (primarily trade debtors and accrued income) in the consolidated statement of financial position at 30 September 2026 when compared to 31 March 2026. The majority of UK revenues are derived from the supply of network capacity rather than the supply of commodities and therefore are not subject to the same seasonal fluctuations as in New York and New England.

Other activities that do not form part of any of the segments in the above table primarily relate to our UK property business together with insurance and corporate activities in the UK and US and the Group’s investments in technology and innovation companies through National Grid Partners.


Six months ended 30 September	2026			2025
	Total sales	Sales between segments1	Sales to third parties	Total sales	Sales between segments1	Sales to third parties
	£m	£m	£m	£m	£m	£m
Operating segments:
UK Electricity Transmission	1,823	(57)	1,766	1,443	(37)	1,406
UK Electricity Distribution	922	(3)	919	901	(5)	896

New England	1,630	—	1,630	1,493	—	1,493
New York	3,107	—	3,107	2,667	—	2,667
National Grid Ventures	516	(23)	493	601	(20)	581
Other2	226	(3)	223	25	(3)	22
Total revenue	8,224	(86)	8,138	7,130	(65)	7,065

Geographical areas:
UK			3,167			2,702
US			4,971			4,363
Total revenue			8,138			7,065

1.Sales between operating segments are priced having regard to the regulatory and legal requirements to which the businesses are subject. The analysis of revenue by geographical area is on the basis of destination. There are no material sales between the UK and US geographical areas.

The principal revenues of the UK Electricity Transmission segment arise from the provision of electricity transmission services and are invoiced to, and collected from, National Energy System Operator (NESO). Amounts are invoiced and settled in equal monthly instalments throughout the financial year. No other single customer contributed 10% or more of the Group’s revenue in either of the periods presented.


	Total operating profit/(loss) before exceptional items and remeasurements		Exceptional items and remeasurements (see note 4)		Total operating profit/(loss) after exceptional items and remeasurements
Six months ended 30 September	2026	2025	2026	2025	2026	2025
	£m	£m	£m	£m	£m	£m
Operating segments:
UK Electricity Transmission	1,147	813	—	(3)	1,147	810
UK Electricity Distribution	477	488	—	—	477	488

New England	92	81	(27)	(20)	65	61
New York	373	73	4	5	377	78
National Grid Ventures	127	187	90	(61)	217	126
Other	(66)	(27)	142	(10)	76	(37)
Total Group	2,150	1,615	209	(89)	2,359	1,526

Geographical areas:
UK	1,713	1,476	146	22	1,859	1,498
US	437	139	63	(111)	500	28
Total Group	2,150	1,615	209	(89)	2,359	1,526


	Total operating profit/(loss) before exceptional items and remeasurements		Exceptional items and remeasurements (see note 4)		Total operating profit/(loss) after exceptional items and remeasurements
Six months ended 30 September	2026	2025	2026	2025	2026	2025
	£m	£m	£m	£m	£m	£m
Reconciliation to profit before tax:
Operating profit	2,150	1,615	209	(89)	2,359	1,526
Share of post-tax results of joint ventures and associates	89	39	—	—	89	39
Finance income	121	206	—	2	121	208
Finance costs	(843)	(884)	4	(63)	(839)	(947)
Total Group	1,517	976	213	(150)	1,730	826


Depreciation, amortisation and impairment	30 September 2026	30 September 2025
	£m	£m
Operating segments:
UK Electricity Transmission	(308)	(278)
UK Electricity Distribution	(145)	(133)
New England	(276)	(236)
New York	(423)	(376)
National Grid Ventures	(75)	(76)
Other	(2)	(3)
Total	(1,229)	(1,102)

Asset type:
Property, plant and equipment	(1,022)	(950)
Non-current intangible assets	(207)	(152)
Total	(1,229)	(1,102)

Capital investment represents additions to property, plant and equipment, prepayments to suppliers to secure production capacity in relation to our capital projects, non-current intangibles and additional equity investments in joint ventures and associates. Capital investments exclude additions for assets or businesses from the point they are classified as held for sale.


	30 September 2026	30 September 2025
	£m	£m
Operating segments:
UK Electricity Transmission	2,888	1,684
UK Electricity Distribution	834	756
New England	1,105	958
New York	1,775	1,585
National Grid Ventures	100	69
Other	5	—
Total	6,707	5,052

Asset type:
Property, plant and equipment	6,047	4,551
Non-current intangible assets	310	323
Equity investments in joint ventures and associates	15	15
Capital expenditure prepayments	335	163
Total	6,707	5,052


	30 September 2026	31 March 2026
	£m	£m
Split by geographical area:
UK	50,781	47,551
US	51,370	49,273
Total	102,151	96,824

Reconciliation to total non-current assets:
Pension assets	2,617	2,507
Financial and other investments	1,898	842
Derivative financial assets	558	623
Non-current assets	107,224	100,796