Power Play in Iver – Data Centre Allowed in Grey Belt

The much-anticipated planning appeal for a major data centre development at Woodlands Park landfill site, Iver, has been allowed.

On 9th July 2025, the Secretary of State granted planning permission for a 72,000 sqm (GEA) facility delivering 90 MW of capacity, overturning Buckinghamshire Council's refusal. This follows an earlier planning application for a much larger scheme (147MW over 3 buildings), that was dismissed in October 2023 by the previous Secretary of State.

This most recent decision further evidences the demonstrable need for data centre development, whilst highlighting the importance of data centres to the UK economy. This decision represents the third such successful recovered appeal for data centre in the Green Belt, following the precedents set at Court Lane, Iver in December 2024 and Abbots Langley in May 2025. This allowed appeal, further strengthens the case for data centre proposals and offers important clarity on the interpretation of 'Grey Belt' status.

The Secretary of State's assessment acknowledged some adverse landscape and visual effects, which were given significant weight in the planning balance. However, these concerns were outweighed by the extensive benefits identified.

These benefits include addressing the urgent need for data centre capacity in the Slough Availability Zone (SAZ), where capacity requirements have risen dramatically from 1,700MW (identified in the Court Lane decision) to a mid-range estimate of 2,486MW needed between 2024 and 2029, projected to reach 2,858MW in the future. The development will also generate substantial direct and indirect employment opportunities, contribute to education and employment initiatives, help mitigate climate change, and deliver biodiversity net gain.

On balance, the Secretary of State concluded that the benefits of the proposal clearly outweighed the identified harms, and that material considerations supported granting planning permission.

A key aspect of this decision was the contrasting views between the Planning Inspector and the Secretary of State regarding the site's 'Grey Belt' status.

The Planning Inspector concluded the site made a strong contribution to Green Belt purpose (a) - checking unrestricted sprawl - arguing the development would appear as "an extended finger of development into the Green Belt and represent an incongruous pattern of development." Consequently, the Inspector determined the site did not qualify as 'Grey Belt' land and applied the Very Special Circumstances test.

However, the Secretary of State disagreed with this assessment, concluding that the proposal was not inappropriate development in the Green Belt. The Secretary of State specifically noted: "...if developed, there would not be an incongruous pattern of development, given the existing residential development extending west along Iver Lane to the south and the National Grid Iver substation to the north. This built development provides a boundary to the north and south of the appeal site. Furthermore, she considered there to be physical features that could restrict and contain development, which include the pattern of built development surrounding the site, the River Colne and the M25. She therefore concluded that the site did not strongly contribute to purpose a)."

This distinction in interpretation between the Inspector and Secretary of State provides valuable insight into how 'Grey Belt' considerations may be applied to future data centre proposals.

JLL benefits from a wealth of experience in respect to Data Centres, offering a 'cradle to grave' service that includes site finding, site selection, planning, advisory, transactions, and facilities management. To discuss any of the matters discussed above or any other planning matter, please contact the team.