No national permitted development right governs basement construction in London, UK. Instead, each of the capital’s 33 boroughs sets its own rules independently, with no requirement that they align. Camden, Kensington and Chelsea, and Westminster maintain some of the strictest basement policies in the country:
Westminster has operated a borough-wide Article 4 direction since 2016, removing permitted development rights for basements entirely and limiting new construction to a single storey covering no more than half the garden. A few miles away, Wandsworth’s policy is comparatively permissive, though it still requires a detailed application for any new excavation.
As a result, an identical basement scheme can clear approval on one side of a borough line, then face months of additional review, revised documentation, and pre-application consultation on the other. The design didn’t change. The rulebook did.
For architects and developers working across multiple boroughs, that inconsistency is more than an administrative headache. If a multi-unit application is refused after months of preparation and design work, the cost is absorbed with nothing to show for it. In London’s residential market, planning risk functions less like a procedural step and more like a line item.
Narrower Path to Appeal
The system meant to correct a wrongful refusal has itself gotten harder to use. From April 2026, the Planning Inspectorate expanded the “written representations” appeal route to cover most householder, minor commercial, and advertisement appeals. It also introduced a new appeal form limiting the applicant’s written case to 250 words. The stated goal is to speed up a notoriously slow system. Government figures put the median determination time for appeals at roughly 23 weeks, with only around a third of appeals succeeding. But the reform has drawn sharp criticism from planning consultants and lawyers. Some have called the word limit “plain ridiculous.” They warn that appellants will struggle to make a full case for anything beyond the simplest scheme, and that the change may create more back-and-forth for developers, councils, and inspectors rather than less.
Matthew Withers, co-founder and director of Stylus Architects, has watched that tension play out from the applicant side. “Government ministers must think this is a great idea, but actually what ends up happening is it really isn’t,” he says. “There’s a limited amount that you can do in 250 words.” His concern echoes the broader practitioner reaction. The appeal mechanism exists precisely because local-level resolution has already failed. Restricting its scope doesn’t resolve the underlying disagreement. It narrows the applicant’s ability to make their case at the one stage designed to correct it.
Withers also points to a structural gap the reform doesn’t address: pre-application access to planners, which determines how many disputes get resolved before they ever reach appeal. “Being able to have a conversation with a planner is few and far between,” he says. “Being able to find solutions to what they deem as problems in your scheme doesn’t happen.” If the government intends to push more disagreements toward resolution at the local level, that assumes local planners are consistently accessible. Withers says that assumption doesn’t match his experience across boroughs.
Constraint as Design Input
Despite the criticism, architects working within this system don’t uniformly treat borough-level variation as pure friction. Understanding what a given borough will and won’t permit forces earlier, more deliberate decisions about massing, orientation, and form. Made under constraint, those decisions sometimes produce a better outcome than an unconstrained brief would have. A basement project limited to a single storey and half a garden, for instance, pushes an architect to resolve daylight, structure, and circulation within a tighter envelope than they might otherwise choose. Site restrictions that rule out expanding a footprint sideways or upward have also led some firms toward built-in energy strategies, like maximizing solar-facing roof area, that a less constrained design might not have prioritized.
Withers frames it in similar terms: “I’m not in the business of changing planning policy. I’m in the business of just accepting what it is and dealing with it.” In his experience, planning timelines that were badly disrupted after Covid have since improved. He credits some of that to relationship-building with local planning departments rather than adversarial dealings. Other firms echo that strategy, since boroughs vary not just in policy but in how approachable their planning officers are in practice.
For firms that take on projects outside London or the UK entirely, the same borough-by-borough logic scales up to a jurisdiction-by-jurisdiction one. Partnering with local architects who understand a given area’s regulatory environment, rather than importing a single approach across markets, is one common way firms manage that variation.
As London’s housing shortage continues to outpace supply, pressure on the planning system isn’t likely to ease. The appeal reforms taking effect this year add a new variable rather than removing an old one. For architects and developers working across the capital’s borough lines, planning fluency has become a core professional skill. Understanding not just what a scheme should look like, but which authority will decide it and under what rules, has become as central to project viability as the design itself.
About the Expert: Matthew Withers is co-founder and director of Stylus Architects, a London-based residential architecture practice now in its tenth year.
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