Britain's digital infrastructure number tripled by definition, then fell 4 percent

The distance between the two measures is £7.6bn ^[1], and none of it is a building site. The statisticians say so themselves: they are not identifying investment outside existing capital formation data, and the wider definition reclassifies a greater share of what was already recorded ^[5]. That is still worth doing, because the old method hunted for structures inside the telecoms industry, and a data centre files its shell under buildings, its servers under hardware and its models under software ^[13]. Nothing in the telecoms line was ever going to find it.

What the wider frame buys is composition. The buildings and structures category, which holds shells alongside fibre and base stations, is 83.8% up on the start of the 2020 pandemic ^[10]. Software and databases has risen almost 95% since 2021 ^[11]. After those two, roughly £1.8bn is left for everything else, hardware included ^[3]. And the longer arc is genuinely steep: by 2023 the total stood 51% above 2019 against 19% for UK business investment as a whole ^[8], which is close to three times the growth rate of the rest of the capital stock ^[8].

Then 2025. On the same basis 2024 was about £11.7bn ^[2], and the release does not say which category gave up the difference. The lines it does describe went up: hardware by 54.6% to its highest since 2006, which the ONS puts down to data centres expanding for cloud and AI ^[12]. It also notes 2025 was the third highest year in a series running back to 1997, while the direction was down, a point Tom Krazit made for The Stack ^[7].

The demand side is not in doubt. AI use among UK firms with ten or more employees went from about 12% in late 2023 to 35% this year on the ONS survey ^[17], on top of the 69% already running cloud systems in 2023 ^[18]. Oxford Economics counted more than 400% growth in the number of UK data centres between 2000 and 2024, as Tom Rees reported for Bloomberg ^[19]. Around 63% of last year's development activity was hyperscale, built and operated by global technology firms for their own use ^[16], so the spending does not arrive through an operator Ofcom supervises. For scale, Ofcom put fixed-network spending by telecoms operators at £6.8bn in 2024, with 77% going into full fibre ^[23]; the narrow ONS measure is a little over half that, on a different year and a different definition ^[9].

What binds is power, not capital. Data centres were designated Critical National Infrastructure in 2024, filed with energy and water ^[15], and both are where the queue forms. Andrew Bailey has warned that AI may have to be rationed if energy capacity runs short, in comments Bloomberg reported ^[25]; an Essex data centre has already waited on a grid connection and the water industry has warned about supply ^[26]. Meanwhile the state's own build slipped: £2bn of the £5bn Project Gigabit programme went out between 2020 and 2025, and the 2025 spending review moved nationwide gigabit coverage from 2030 to 2032 ^[24], leaving 60% of the money and two more years to spend it in ^[6].

The definition widened on Monday ^[4]. Next year's release is the first where a fall cannot be charged to bookkeeping.