Three data centres with 141 backup generators are planned on 23.5 hectares of green belt off Poyle Road. What the plans show, and how to comment by 20 October.

Plans for three more data centres on green belt land at Poyle have been lodged with Slough Borough Council. The site is 23.5 hectares of former farmland west of Manor Farm, Poyle Road, in Colnbrook. It sits next to the data centre the government approved on appeal in June.

The application, reference P/21160/000, was received on 16 September 2026. The applicant is Manor Farm Propco Limited, the same company behind the approved scheme. The details come from the council’s planning register and the 226 documents filed with it.

The site is about 5.3 kilometres south east of Slough town centre and 1.6 kilometres west of Heathrow, according to the applicant’s environmental statement.

What is proposed

The scheme is called Manor Farm West. The developer’s non-technical summary describes three data centre buildings, known as MFW1, MFW2 and MFW3. MFW1 would sit in the north of the site and the other two in the south.

The plans include:

  • about 124,000 square metres of floorspace, measured externally
  • an assumed installed IT load of 72 MW per building, 216 MW in total
  • data halls up to 30.95 metres high including rooftop cooling plant
  • office blocks at the corners of each building, up to 19.6 metres high
  • 141 emergency backup generators, 47 per building, with fuel storage
  • an electricity substation and a guardhouse for each building
  • 254 car parking spaces, and a new roundabout at the Poyle Road entrance
  • a short diversion of a drainage ditch in the south east of the site

The generators would only run in a power cut and during routine testing, the summary says. It assumes diesel “as the worst case”, although “cleaner fuels are proposed where this is technically and commercially feasible”.

The data centres would be linked to the national grid by an underground cable of about 8.6 kilometres, running mostly under existing roads to Laleham substation in Spelthorne. That cable needs separate planning applications.

How it compares with the scheme next door

The application form gives 122,544 square metres of new gross internal floorspace. The data centre the government approved on the neighbouring land in June has about 36,368 square metres, according to the Secretary of State’s decision letter. We covered that decision in our report on the Slough data centre petition.

Bar chart of new gross internal floorspace in square metres. The Manor Farm data centre approved on appeal in June 2026 has 36,368. The proposed Manor Farm West scheme of three buildings has 122,544.
The new application is more than three times the size of the scheme already approved on the neighbouring land. Chart by Slough Daily
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The developer says the two schemes are separate. “Each could be built and operated without depending on the other,” the summary says. Because they sit side by side and partly overlap, its environmental assessment looks at their combined effects.

Tritax Big Box REIT bought the 74-acre Manor Farm site for an initial £70 million, according to the company’s own announcement of the purchase.

The green belt argument

The site is in the Metropolitan Green Belt, a designated Strategic Gap and the Colne Valley Regional Park. The developer’s case rests on “grey belt”, the category the government created in December 2024 for green belt land that does not strongly serve its main purposes.

Its Grey Belt Appraisal, by Pegasus Group, concludes that the site should be treated as grey belt. It leans on the June appeal. There, the inspector found the Manor Farm land was grey belt, and the Secretary of State agreed.

The applicant also argues there is no other suitable site. Its alternative sites study “concluded that no other suitable and available sites could meet the operational requirements within the required timescale”.

What the developer’s own assessment finds

The environmental statement reports some effects as significant even after mitigation.

  • Views. Significant, permanent visual effects for some nearby homes, for people using the footpath through Poyle Poplars and for members of Datchet Water Sailing Club.
  • Carbon. About 3,818,342 tonnes of carbon dioxide equivalent over a 60-year life. The statement rates the operational and whole-life effect as “moderate adverse and significant”.
  • Wider views. Moderate adverse effects for residents on the southern edge of the Colnbrook Conservation Area, and for visitors to Coopers Hill, Runnymede and the East Terrace at Windsor Castle.

It finds no significant effects on air quality, flooding or wildlife sites once mitigation is in place. Noise and traffic were scoped out of the full assessment because separate studies found no likely significant effect.

On water, the statement says the buildings would use sealed, closed-loop cooling. It estimates 1,892 cubic metres of process and cooling water a year once complete. Thames Water has been asked to confirm the connection point and any upgrades needed.

Jobs, rates and building work

  • Jobs. Between 110 and 580 full-time jobs once running, according to the summary. The developer’s own assessment rates that as “minor beneficial (not significant)”.
  • Construction. About two years and eight months, finishing in 2030 if approved. The economic statement puts the average workforce at 580 over that period.
  • Lorries. Construction traffic would come up from junction 14 of the M25, which the summary says “would avoid HGVs travelling through Colnbrook”.
  • Business rates. Up to £12 million a year, the economic statement estimates, part of which the council would keep.

The plans also include about 7.6 hectares of publicly accessible landscape on the west and north of the site. There would be a walking and cycling route of about a kilometre and an outdoor learning area for schools and community groups.

What people said at the exhibition

The developer held one public exhibition, at St Thomas’s Church in Colnbrook on 26 August. Its Statement of Community Engagement says 46 people attended and 8 feedback forms came back.

Residents were “most concerned about noise, flood risk, the design of the buildings, relatively low employment figures and the perceived impact on local wildlife”, the statement records. One form asked: “how will residents be affected by another data centre added into a community with 40 data centres already?”

The council’s position

Councillors had a motion on data centres before full council on 24 September. It was proposed by Councillor Muvvala and seconded by Councillor Shaik, according to the published motions paper.

The motion asks the council to:

  • write to the government asking it to publish evidence on the cumulative impacts and benefits of data centres, including energy, water, grid capacity and emissions
  • make sure the evidence behind the new Local Plan covers data centre growth
  • press operators for local jobs, apprenticeships and environmental benefits
  • publish a webpage listing existing, consented and proposed data centres, with their planning status and section 106 obligations, by 31 December 2026

The council’s minutes of that meeting, which will record the vote, have not yet been published.

The resident petition asking the council to pause data centre approvals had 776 signatures on 29 September, on the council’s petitions page. It closes on 16 November.

What it means for you

If you live in Colnbrook or Poyle, this is the application to read. It is fixed in detail, not outline, so the heights, layout and generator numbers are what would be built.

  • Comment by 20 October 2026. That is the statutory expiry date on the council’s register. Comments go through the application page, and you need to register an account first.
  • Quote P/21160/000 in anything you send.
  • Decision. The council’s target date is 16 December 2026.
  • Read the summary first. The 25-page non-technical summary is on the application page. Hard copies are available from the developer’s planning consultant, Quod, on 020 3597 1000, quoting Q250317.

Remember that the council did not have the last word on the scheme next door. It failed to decide that application in time, the developer appealed, and a minister approved it. Live applications across the borough are listed on Slough planning news.

Sources