Hilfield Park data centre campus (former Mercure Hotel, Tylers Way), Hertsmere (Ark Data Centres)
Ark Data Centres
Ark Data Centres has applied to Hertsmere Borough Council (25/1781/FUL) to clear the former Mercure Hotel site on Tylers Way, off the A41 near Watford, and build a data centre campus of free-standing data centre buildings with energy, power and water infrastructure. Ark puts the investment at more than £2.5bn. DCD reports 200MW for the campus and a 120MW power reservation at Elstree substation that passed to Ark with the site. The site is in the Green Belt and the scheme drew 1,184 objections and 4 support comments. Council officers recommend approval, and the planning committee is due to decide it on 5 November 2026.
Reality Score
Early stage: worth a watching brief.
Supplying this project? See the Market Entry Sprint →Key facts
- Operator / developer
- Ark Data Centres
- Location
- Site of former Mercure Hotel and land to south east, Tylers Way, Watford, WD25 8JH, East of England, United Kingdom
- Status
- Planning submitted
- Facility type
- Data centre
- AI relevance
- Not stated
- Floor area
- 137,900 m²
- Stated investment
- £2,500,000,000
Power & grid
- Published capacity
- 120 MW — Published grid-connection capacityThe connection capacity secured or applied for, which is not the same as demand.
- 200 MW — Published campus build-out capacityA whole-campus figure covering all phases. It is not current operational capacity.
- 200 MW — Reported capacity, definition not publishedA megawatt figure was reported but the source does not define what it measures, so it is excluded from every total.
- Share of UK tracked capacity
- 32.4% of published grid-connection capacity
- Power
- 200MW reported for the campus (DCD). 120MW power reservation at Elstree substation transferred to Ark with the site sale (DCD); no connection date evidenced. Ark says a direct grid connection separate from local homes.
Planning
- Council
- Hertsmere Borough Council
- Planning route
- Local planning (TCPA)
- Planning reference
- 25/1781/FUL
- Planning decision
- Full application 25/1781/FUL registered Dec 2025; officers recommend approval; planning committee 5 Nov 2026; undetermined.
- Green belt
- Yes
- Recorded objections
- 1,184
- Recorded support
- 4
Timeline
Ark Data Centres launches public consultation on a data centre campus on the former Mercure Hotel site.
SourceFull application 25/1781/FUL registered by Hertsmere Borough Council (week of 15 to 28 Dec 2025).
SourceOfficers recommend approval; planning committee to decide on 5 Nov 2026 (1,184 objections).
Source
Sources
- Planning applications registered 15/12/2025 to 28/12/2025 (25/1781/FUL)
Secondary source · Hertsmere Borough Council (primary) · 2025-12-28
- £2.5bn data centre: officers recommend approval ahead of 5 Nov committee
Secondary source · Watford Observer via Yahoo News (secondary) · 2026-10-28
- Ark plans 200MW data center campus in Watford, UK
Secondary source · DCD (secondary) · 2025-10
- Daylight and Sunlight Report, Former Mercure Hotel, Tylers Way
Secondary source · eb7 for Ark Estates 5 Ltd (application document) · 2025-12-08
Last verified
31 October 2026
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