The Tadley flats appeal for nine apartments near the Atomic Weapons Establishment at Aldermaston has been dismissed because the extra residents would place unacceptable pressure on emergency arrangements for a nuclear incident. The inspector accepted that the proposal would deliver housing on previously developed land, within the settlement boundary, at a time of weak housing supply. Those benefits could not outweigh the public safety evidence.
The decision, issued on 20 October 2026, relates to Old Kiln House, Silchester Road, Tadley, and Basingstoke and Deane Borough Council’s application reference 24/02433/FUL. Inspector Alexander O’Doherty’s reasoning is important beyond a nine-home scheme: planning policy for safeguarded hazardous sites asks not only about the likelihood of an incident but whether emergency arrangements would still work if more people needed help.
The Tadley flats appeal also exposes the risks of inconsistent distance measurements, relying on untested mitigation proposals, and promising affordable homes without a completed legal obligation.
The Tadley flats appeal and the emergency planning zone
The proposed development was for nine two-bedroom flats and associated access and parking on land alongside the existing Old Kiln House building. The property is within the Detailed Emergency Planning Zone around AWE, the licensed nuclear establishment involved in the UK’s defence programme. Emergency-planning zones are designed to support protective action in the event of a radiation emergency. They are not simply a generic development exclusion zone.
Policy SS7 of the Basingstoke and Deane Local Plan 2011 to 2029 requires relevant development in the area to be considered against the ability of the off-site nuclear emergency plan to accommodate its population. The Office for Nuclear Regulation (ONR), emergency planning authorities and other specialist bodies were central to the decision.
The inspector referred to the off-site emergency plan as an operational arrangement for multiple responding agencies. It must account for immediate protective action, possible displacement and evacuation, places for reception and rest, radiation monitoring, specialist equipment, staff and longer-term accommodation for those affected. These resources are finite, even where the likelihood of a serious incident is low.
At application and appeal stages, evidence came from West Berkshire Council, Hampshire County Council, the ONR and AWE Nuclear Security Technologies, acting for AWE and the Ministry of Defence. Each raised strong objections. The emergency-planning evidence was that the existing arrangements were already stretched, without these nine flats or other consented but unbuilt development.
Why the disputed distance mattered
The Tadley flats appeal included several different measurements between the proposed housing site and the nuclear establishment. Figures quoted in the evidence included roughly 530, 570, 600, 615 and 700 metres. The appellant relied on longer distances, while the council put forward mapping at approximately 570 metres and earlier officer material quoted 530 metres.
Inspector O’Doherty considered that different start and end points were likely being used. The appellant had not demonstrated that the council’s mapping was wrong, and the inspector was not persuaded that the site could reliably be said to lie more than 600 metres from AWE. That distinction was relevant to the likelihood of urgent protective action and the type of temporary or longer-term accommodation needed.
The dispute illustrates a wider technical point. Where policy or specialist advice depends on distance from a hazardous installation, the precise reference points and measurement method should be agreed early. Several measurements without a common basis do not provide an adequate planning assessment.
Twenty-one extra residents and cumulative pressure
Hampshire’s emergency planning team estimated that the nine apartments could accommodate an average of 21.6 additional residents. The concern was not just the physical proximity of the building. An increase in the population of a sector of the emergency-planning zone adds to the number of people who may need instructions, transport, medical monitoring, shelter and support.
The inspector drew on earlier decisions near AWE in which decision-makers had accepted evidence that the off-site plan lacked spare capacity. No convincing evidence demonstrated that this position had improved. The Tadley flats appeal was assessed against the cumulative effect of this scheme and other development on emergency responders, rather than treating nine flats as too small to matter.
The appellant submitted a radiological impact assessment suggesting the direct risk from a major incident was very small. That did not answer the capacity question. The inspector noted the distinction between the probability of an incident, its potential consequences, and the practical capacity to respond if an incident occurred. Some source information in the assessment was also criticised by West Berkshire’s emergency planners as outdated or inaccurate, reducing its evidential weight.
A proposed management company, said to be capable of assisting with rehousing, did not supply the missing assurance. No completed planning obligation was before the inspector to secure the proposal. Nor was the inspector persuaded that a commercial Class E fallback would necessarily create greater emergency planning demands than residential use, since people living in flats may be at home overnight and may need longer-term accommodation if displaced.
Substantial housing benefits did not carry the balance
There were positive planning considerations. The site is within Tadley’s settlement boundary, close to facilities and public transport. The proposed nine two-bedroom flats would meet an identified type of housing need and make more intensive use of developed land. The appellant cited a housing land supply of only 3.2 years. Tadley Town Council and some interested parties supported the proposal.
The inspector attributed substantial weight to the housing and land-use benefits. However, he gave very substantial weight to the public safety concerns and found conflict with Local Plan Policy SS7 and the national policy governing proposals within emergency-planning zones. The Tadley flats appeal therefore failed even when assessed against the August 2026 National Planning Policy Framework’s support for additional homes and better use of land.
An intention to offer the flats to local people at affordable rents also carried no positive weight because it had not been secured through an executed planning obligation. The inspector did not treat that unenforceable intention as a reduction in net population growth in the emergency planning zone. Biodiversity net gain at the statutory 10% minimum was considered neutral rather than an extra reason to approve.
The inspector also noted evidence about the wider national-security implications were an emergency plan to be declared inadequate and thereby potentially constrain AWE operations. That point reinforced the importance of the specialist evidence; it was not a separate finding that an incident was likely to occur.
What applicants around safeguarded sites should do
The Tadley flats appeal confirms that residential development near a hazardous installation needs early engagement with the relevant safety and emergency planning authorities. Applicants should establish whether population growth can be accommodated by existing plans, agree defensible measurement methods, and test proposed mitigation with the organisations responsible for delivery.
Affordable-housing commitments, management-company arrangements and other proposals intended to address impacts need legal mechanisms capable of binding the development. A promise made in a planning statement may have little weight if nobody can enforce it. For policy context, see our guide to the 2026 National Planning Policy Framework.
This is an England planning appeal decision under section 78, not a court ruling and not a general ban on all development near AWE. The Planning Inspectorate appeal record 6011464 contains the decision. It is also available via AppealBase.
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