What happened

National Grid has named the contractors on its North West London Upgrade, a £1bn transmission scheme running from Sundon substation in Bedfordshire, through Elstree in Hertfordshire, to St John's Wood in London. Construction News and Construction Enquirer reported this month that Laing O'Rourke has taken the substation works at Letchmore Heath, Elstree and St John's Wood, while the Hochtief Murphy joint venture, known as HMJV, will handle cable installation and the upgrade of the existing tunnel between Elstree and St John's Wood. Hyundai Electric will supply and install the transformers and other major electrical plant, and Siemens Energy is providing shunt reactors for the Elstree substation.

The scheme exists because of one thing: data centre demand. National Grid says the works will connect five new data centres in Hertfordshire, equivalent to 1GW of demand, to the existing Elstree substation via a new 132kV facility at Letchmore Heath. Over 200km of overhead line between Sundon and Elstree is being upgraded, alongside 60km of new cable through the Elstree to St John's Wood tunnel.

Why it matters

This is one of the clearest signals yet that the AI and data centre boom is now a construction story, not just a technology one. Every hyperscale data centre needs grid capacity before it needs a roof, and National Grid's own pipeline has dozens of similar upgrades queued up behind this one as operators wait for connections across the South East and beyond. For contractors, that means transmission and substation work, historically a niche corner of the market dominated by a handful of specialist firms, is becoming a mainstream growth line that main contractors like Laing O'Rourke are now chasing directly.

What it means for your career

This is a good moment to take electrical and power infrastructure experience seriously if you have it, or to go and get some if you don't. Substation construction, high voltage cabling and tunnel works are specialist disciplines, and the site management, commercial and engineering roles behind them are being advertised well above general building rates. A Principal Contractor Site Manager role on this scheme alone was recently listed at £550 to £650 a day.

For QSs and commercial managers, power infrastructure contracts tend to run on NEC frameworks with long programmes and complex interfaces with the client's own engineers, so experience on rail or water infrastructure schemes translates well. If you're based in the Home Counties or North West London and want to move without relocating, this scheme runs for several years and will need site teams from groundworks right through to testing and commissioning. Laing O'Rourke's power and energy division, and the two firms inside HMJV, are the names to watch for direct hires and subcontract packages as the programme mobilises.