Sequential test sinks Aldi’s Stanmore supermarket appeal

Sequential test shortcomings have sunk Aldi’s appeal for a new Stanmore food store after Inspector John Longmuir found the town-centre sequential test had not fully explored Anmer Lodge.

The supermarket operator wanted to redevelop the former National Grid site on Marsh Lane with a new Class E(a) food store, warehouse, staff facilities, access, parking and landscaping. Inspector John Longmuir dismissed appeal 6005822 on 30th September 2026 after an inquiry held on 4th, 5th, 6th and 11th August.

The result turns on a useful distinction for retail planning. Harrow accepted Aldi’s Retail Impact Assessment and the Inspector agreed the store would not significantly adversely affect nearby centres. But that did not answer the separate question of whether a more central site should have been used first.

Anmer Lodge proved decisive

Both main parties agreed the Marsh Lane site was out of centre. That brought Harrow Local Plan Policy LE1 and the August 2026 National Planning Policy Framework sequential test into play.

Harrow’s case focused on Anmer Lodge, behind The Broadway in Stanmore. The Harrow Local Plan 2021 to 2041, adopted on 24th March 2026, allocates the site for mixed-use development including a food store. The Local Plan examination had also recognised it as an appropriate location for a supermarket.

There was history behind the argument. A 2014 permission at Anmer Lodge included 818 square metres of retail floorspace and 50 parking spaces. It had been implemented sufficiently for a lawful development certificate to confirm that the permission remained extant, although little further work had taken place.

Part of the wider allocation had since been developed for housing, reducing the land available for a store. Aldi argued that this would constrain floorspace, product range, aisle widths and parking. There had also been earlier doubts over commercial delivery, including a 2021 pre-application scheme which was not pursued.

For the Inspector, those difficulties were evidence to weigh, not a basis for striking Anmer Lodge out of the sequential exercise. More recent developer interest also suggested the site still had momentum, while the adopted allocation continued to contemplate food retail.

A rejected land offer did not settle availability

Aldi had approached the Anmer Lodge landowner and made an offer to acquire the site, but the offer was rejected. That might sound like a clean answer to availability. The Inspector did not see it that way.

Harrow questioned whether the offer reflected an appropriate land value and whether Aldi had sought too much floorspace and parking. The evidence did not allow the Inspector to determine the significance of the offer value either way.

Crucially, a rejected offer was not treated as proof that a food store could not be delivered. The decision records that the offer itself made it difficult to rule out the potential for some form of food retail on the allocated site.

There had been no market testing by Harrow, and earlier development proposals had encountered viability and delivery problems. Even so, the Inspector placed weight on the fact that Anmer Lodge had survived the recent Local Plan examination as a mixed-use allocation which specifically included supermarket provision.

Flexibility was at the heart of the sequential test

The August 2026 NPPF did not materially change the sequential test applied at the inquiry. Policy TC3 still requires main town centre uses to look first to town centres, then edge-of-centre locations, with out-of-centre sites considered only when suitable alternatives are not available, or are not expected to become available within a reasonable period.

It also requires applicants and planning authorities to exercise flexibility over matters such as format and scale. That point mattered because Anmer Lodge could not necessarily accommodate Aldi’s Marsh Lane scheme in exactly the same form.

The Inspector accepted that the reduced Anmer Lodge site might mean a smaller store, narrower aisles, a reduced range or less parking. But the sequential test does not ask whether an alternative can reproduce the application scheme unchanged. The question is whether reasonable flexibility has been used to explore a more central opportunity properly.

Aldi also relied on evidence of customer need. Its modelling used a five-minute drive-time catchment and suggested some unmet local demand, while the nearest existing Aldi was beyond an eight-minute drive time. The Inspector accepted that this indicated some local need, but said it “would not trump the sequential test”.

His overall conclusion was that the evidence remained conflicting and was not clear enough to discount food retail at Anmer Lodge. In his words, “the sequential test has not been fully explored”.

Retail impact was a separate test

That conclusion is the most important part of the appeal for anyone preparing an out-of-centre retail application.

Aldi did not fail because Harrow had proved that the proposed supermarket would damage Stanmore or other nearby centres. In fact, the opposite happened on the impact evidence. Aldi submitted a Retail Impact Study, Harrow accepted its methodology and findings, and the Inspector agreed there would be no significant adverse impact on local centres.

But retail impact and the sequential test are not interchangeable. The impact assessment asks what effect the proposed development would have on centres. The sequential test asks whether the development should be located in a more central place in the first place.

Passing one does not cure failure on the other. On the Inspector’s findings, the Marsh Lane scheme conflicted with Policy LE1 and the NPPF because the sequential exercise had not gone far enough, irrespective of the accepted impact assessment.

Aldi won several of the other arguments

The dismissal should not be read as a wholesale rejection of redevelopment at Marsh Lane.

The former gasworks site had been underused since 2012 and was largely vacant. Its triangular shape and gas infrastructure easements constrained the developable area, but the Inspector found the proposed layout made efficient use of the site. Reusing brownfield land was a positive factor.

The economic case also carried weight. The proposal would have created around 40 jobs, with employment and training measures secured through the planning obligation. The Inspector did not find an overriding need to retain the land for industrial use and concluded that the proposal complied with the relevant economic policies.

Highway safety was not a reason to dismiss the scheme. The proposed access onto Marsh Lane had adequate visibility, the road network had capacity, and it had passed a Stage 1 Road Safety Audit. The Inspector found the access safe.

There was, however, a separate policy tension over the amount of parking. The proposal included 94 spaces, well above the London Plan figure discussed at the inquiry, creating conflict with parts of Policies T1 and T6.3. At the same time, Harrow’s highways team had accepted the level of parking as necessary for expected demand, and the Inspector found no safety objection.

Ecology and surface-water flooding were also capable of being addressed. Surveys found no protected species or habitat on the cleared site, while landscaping and boundary changes would improve ecological conditions. A revised flood strategy kept the south-west corner free to preserve flood-flow routes, and Harrow withdrew its objection.

Significant benefits were not enough

The planning balance therefore contained plenty in Aldi’s favour. The scheme would bring a largely vacant brownfield site back into productive use, create jobs, deliver biodiversity net gain, provide an energy-efficient building and support new bus stops.

The Inspector described those benefits collectively as significant. They still did not outweigh the development-plan conflict created by the sequential issue.

Policy LE1 was treated as the most important local policy for the decision. With Anmer Lodge still allocated for mixed use including a supermarket, and with its food-retail potential not convincingly ruled out, the Inspector gave substantial weight to the conflict with the development plan.

That is why the accepted impact assessment matters so much to the story. The appeal demonstrates that an out-of-centre retailer can show no significant adverse impact on existing centres, win on brownfield reuse, jobs, access, ecology and flooding, yet still lose if the sequential test has not been worked through with enough flexibility.

Planning Geek’s town-centre sequential test guide explains the policy test in more detail. The Harrow inquiry library contains the parties’ inquiry documents, while the Planning Inspectorate appeal record remains the official online case record.