The Most Restrictive Ten

The original paper drew a distinction it did not fully work out: the difference between a borough that is hard because an adopted policy makes it hard, and a borough that is hard because it has decided to be. The first follow-up read the permissive end of the table; this essay takes the distinction to the opposite extreme, the ten boroughs that approve furthest below what their caseload should yield. Running the plan audit across all ten produces a sharper result than the binary the first paper proposed. Restrictiveness does not divide in two. It divides in three, and the three are not equally defensible.

One kind of restriction is written into a plan to protect family-sized homes from being carved into flats. A second is written down too, but as a general amenity and garden policy the plan never aimed at small sites, now doing the work a targeted rule would have to justify. A third is written nowhere at all, and in the most striking case the plan says the opposite. Six of London's most restrictive boroughs can name a policy that accounts for their restriction. Four cannot, and one of those four restricts in direct contradiction of its own adopted text.

§1 Why these ten: the boroughs that say no

The differential measures approvals granted against the approvals London-average decision behaviour would have produced on the same caseload, holding site type, transport accessibility, conservation status and unit count constant. The ten boroughs below are the ten with the largest negative residual, the ten that, given what they received, produced the fewest approvals. Four of them are also among London's cheapest. The interest of the other six is that they are not uniformly cheap: Barnet, Kingston and Waltham Forest sit in the middle of London's price distribution, and Lambeth is a relatively expensive inner-south-London borough rather than an outer or eastern one, so whatever produces their restriction, it is not poverty.

The colour split is the essay. It does not follow price, and it does not follow the size of the differential: Barnet at −8.7 has a clearer policy basis than Waltham Forest at −15.3. It follows the one thing that turns out to matter: whether, when you open the adopted plan, you find a policy that accounts for the restriction the data records. For six of these boroughs you do. For four you do not.

§2 What the number hides: two signatures of restriction

As at the other ends of the table, the borough figure resolves into something more legible once it is broken to site type. Here the disaggregation does more than sharpen the picture; it sorts the ten boroughs into two distinct shapes, and the shape turns out to carry most of the verdict before a single plan is read.

The uniform signature is a whole row of red, and its tell is the demolish-and-rebuild column: it too runs negative. Croydon is the textbook case, depressed on all six measurable typologies; Havering, Waltham Forest, Kingston and Lambeth share the shape on the cells they have volume in, hard on conversions and on rebuild together. A restriction spread this evenly is hard to read off a development plan, because plans constrain kinds of development, and a borough hostile to every kind at once is exercising a general disposition rather than applying a particular rule. The conversion signature is the opposite: a single red column over conversions, at Barking & Dagenham, Newham, Hounslow, Tower Hamlets and Barnet, beside a rebuild figure that is neutral or positive. That is the fingerprint of a family-housing policy, resisting the subdivision of houses into flats while leaving ordinary new building alone. The two shapes do most of the sorting; the plan audit finishes it, because among the four boroughs that carry the uniform signature beside Croydon, one, Lambeth, can point to an adopted amenity policy where the other three cannot.

§3 The unexplained four

Four boroughs carry the uniform signature, and in each the plan audit comes back the same way: there is no adopted small-sites policy that compels the restriction the data records. Havering defends its restraint openly, but the defence is a town-centre growth strategy; its development-management policies are the ordinary character and amenity tests almost every borough carries, with no density cap, garden bar or conversion restriction in the adopted text, and when a backland refusal was appealed at 20 Parsonage Road the Inspector found the scheme complied with Havering's own policies. Croydon revoked its restrictive suburban design guide in 2022 and stayed low and uniform anyway, on a plan that is broadly conformant and even contains an intensification policy. Kingston has no anti-rebuild policy, no loss-of-family-housing policy and no garden embargo; when its character objection was tested on appeal at Lime Grove the Inspector rejected it, and the scheme fell instead on a locally elevated amenity standard.

Waltham Forest is the sharpest of the four, because its plan does not merely fail to compel the restriction; it points the other way. Its adopted Local Plan promotes small-site intensification in terms (the relevant policy "will be promoted"; small-site proposals "will generally be supported"), and its character framework is not mapped across the borough but applied case by case at pre-application, on a requirement for "clear and compelling justification". When a small scheme was refused and appealed, the dismissal rested on amenity and family-housing standards, not on the intensification policy at all. A borough whose plan says yes, whose outcomes say no, and whose refusals are defended on everything except the policy that is supposed to govern them, is restricting on a posture its own plan does not contain. That is the definition of the unexplained category, and it is the one the first paper said belonged in a transparency regime rather than a plan-examination defence.

§4 The legitimate six: family housing and amenity

The other six boroughs can each point to an adopted policy that accounts for the shape of their restriction, though the policies protect two very different things. Five protect family housing. Barking & Dagenham's DMH5 and Newham's longstanding family-housing priority resist the loss of dwellings capable of housing a family with children; Tower Hamlets' Policy S.H1 protects the supply of self-contained and family-sized homes and has been given significant weight at appeal; Barnet's Policy HOU03 permits the conversion of a family house into flats only where a family-sized unit is re-provided at ground floor, reinforced by a borough-wide Article 4 direction removing the permitted-development route to small HMOs; Hounslow's Policy SC6 gates conversions behind a floor-area threshold and a required ground-floor family unit, while its Policy SC4 leaves demolish-and-rebuild to ordinary design and density judgement, which is why its conversion column is the red one while its rebuild figure sits close to neutral. In each the conversion column is the red one, the policy names conversions as the thing it constrains, and the restriction is the visible cost of a deliberate choice to keep family homes whole in some of London's most pressured housing markets. That is a defensible distributional aim, and it is exactly the kind of legitimate local choice the original paper said the differential must leave room for.

One protects residential amenity, and it is the most contestable of the six. Lambeth's restriction is also written down, but at one remove: its Local Plan supports housing supply and windfall density in general terms under Policy H1, then gates the specifics through the garden, amenity, access and servicing tests of Policy Q14. Unlike the family-housing boroughs, its restriction is not concentrated on a single typology. It is uniform, hard on conversions (−15), demolish-and-rebuild (−19) and mid-terrace (−36) alike, which is what a general amenity policy applied across the board tends to produce. The restriction is plan-traceable and, on its own terms, lawful. But the thing it protects is amenity and garden land, not a housing need, and a borough whose general design policy does across every kind of small site the work a targeted policy would have to justify is making a contestable public-interest claim in a way that a borough protecting family homes is not. Lambeth is the case that shows "plan-backed" and "beyond reproach" are not the same verdict, and that the line between a written account and a posture can run through a single borough. Its restriction is explained; whether a generic amenity policy should carry that much weight across the whole small-sites cohort is a fair question for a borough sitting below its housing target, against a 74 per cent Housing Delivery Test.

§5 The verdicts

§6 Restriction is a choice, not a shortfall

A natural defence of a restrictive borough is that it is simply struggling to deliver, that low approvals reflect a hard market, not a hard posture. The Housing Delivery Test, which measures each borough's completions against its requirement, removes that defence for much of this group. Waltham Forest restricts small sites while passing the test at 119 per cent; Croydon passes at 160, Hounslow at 108, and Barnet at 104. These are not boroughs failing to build. They are boroughs meeting their housing numbers on larger sites and declining the small-site homes on top, which means, for them, small-site restriction is a positive choice exercised from a position of delivery comfort, not a symptom of distress.

The boroughs on the other side of the test are in a different but no more flattering position. Havering at 61 per cent, Barking & Dagenham at 66, Lambeth at 74 and Kingston at 48 are all under the threshold that triggers the presumption in favour of sustainable development, and all are refusing the small-site homes that would help close the gap. For the legitimate boroughs that is a coherent trade: they have judged family housing or residential amenity worth the delivery cost, and the plan says so. For the unexplained ones it is harder to defend: a borough below its housing target, refusing compliant small schemes on a posture its plan does not contain, is paying twice, once in homes unbuilt and once in the appeal costs and presumption exposure that an undocumented restriction invites.

§7 The appeal record: refusals stick

The appeal record is easy to misread in both directions; what the Planning Inspectorate does and does not contribute here needs to be stated plainly. Restrictive boroughs are not, on the whole, being overturned: across the matched cohort the hardest boroughs lose around sixteen per cent of decided appeals, below the permissive boroughs' twenty-four, and several of these ten sit lower still: Newham's conversion refusals were upheld outright, Waltham Forest is overturned at about twelve per cent, Tower Hamlets at seventeen. Only about six in a hundred refusals are appealed in the first place. A refusal in these boroughs is, in practice, the end of the road, and the Inspectorate is not routinely reversing it.

But a low overturn rate does not license the unexplained boroughs, for the reason the first essay set out and this group illustrates cleanly. When Waltham Forest's refusal was upheld, it was upheld on amenity and family-housing standards, not on the intensification posture that actually drove the borough below expectation. There is almost always some generic policy on which a defensible dismissal can rest, which is precisely why the appeal rate cannot distinguish a borough applying a real policy from a borough applying a posture and reaching for a policy afterward. The Inspectorate confirms the floor: these are not capricious boroughs whose decisions collapse on review. It cannot draw the line between the legitimate and the unexplained. Only the plan can, which is why the audit, not the appeal statistics, carries the verdict.

§8 The spine: Waltham Forest, whose plan says yes

Two of these boroughs sit close together on the table and far apart on legitimacy, and the pair makes the essay's case. Tower Hamlets and Waltham Forest are both inner-edge London boroughs that come down hard on conversions, all but level with each other on that cell once the cut is made. Tower Hamlets restricts on Policy S.H1, an adopted policy that protects family-sized homes and has held up under an Inspector's scrutiny; its number is the price of a written, defended choice. Waltham Forest restricts on nothing its plan contains, a plan that, read plainly, encourages exactly the small-site intensification the borough's officers decline, and defends the declines, when pushed, on the general amenity policies every borough carries. Same region, all but identical where they refuse conversions, opposite verdict: one borough has put its restriction in writing and can be held to it at examination, the other has kept it out of writing and cannot. The productive question the first paper framed for Havering applies with equal force to Waltham Forest, and it is not an accusation but an enquiry: your plan says yes, so what are you doing that it does not?

§9 Conclusion

The original paper proposed that a negative differential could be legitimate or not, and left the test for later. Run across London's ten most restrictive boroughs, the test returns three answers rather than two. Five boroughs restrict to protect family housing, on policies named in the plan and upheld on appeal. One restricts through a general amenity policy that bites hardest on the awkward plot, plan-traceable but resting on a public-interest claim that is far more contestable. Four restrict on nothing their plans contain, uniformly, across every typology, in one case in flat contradiction of a plan that promotes the very thing the borough refuses, and several do it while comfortably meeting their housing targets, which removes the excuse of necessity. We found the restriction in the differential; the type cut sorted it into its two signatures; the plan audit decided which were licensed. The league table called all ten of these boroughs restrictive. It could not tell you that six of them are restricting on a policy you can read and four on a disposition you cannot, and that distinction, not the ranking, is the one a borough has to answer for.

Sources & confidence

Outcome differentials and type-disaggregated cells: London small-sites planning dataset (LSSPD), build 4 June 2026 (borough_differential.csv, type_differential_cells.csv). Appeal overturn: LSSPD matched-appeal cohort, London 21.0%, hard boroughs ~16% (Waltham Forest 12.2%, Tower Hamlets 16.7%, Newham 0%, Kingston 25.9%, Barnet 27.3%). Housing Delivery Test results are the most recent published measurement (Waltham Forest 119%, Barnet 104%, Hounslow 108%, Croydon 160%, Pass; Havering 61%, Barking & Dagenham 66%, Lambeth 74%, Kingston 48%, Presumption; Tower Hamlets 92%, Action plan). Plan audit: each borough's adopted (and where relevant emerging) Local Plan: Waltham Forest LP1 (adopted 29 February 2024, Policies 8/19/20); Tower Hamlets Local Plan 2031 (adopted 15 January 2020, Policy S.H1); Barnet Local Plan (adopted 4 March 2025, Policy HOU03; HMO Article 4 in force 2016); Lambeth Local Plan 2020–2035 (adopted 22 September 2021, Policies H1/Q14); Hounslow Local Plan (adopted 15 September 2015, Policies SC4/SC6); Kingston Core Strategy (adopted 2012, Policies CS8/DM10 + Residential Design SPD); plus Havering, Croydon, Barking & Dagenham and Newham as audited in The Affordable Ten.

What this can and cannot tell you. The descriptive claims are firm: these ten boroughs approve below their caseload-expected rate, their restriction takes one of three type-level shapes, and their adopted plans range from actively promoting small sites (Waltham Forest) to actively constraining them (Tower Hamlets, Barnet, Hounslow). The legitimacy verdict is an interpretation of the adopted plan text, not a legal ruling; the Newham verdict is provisional pending adoption of its emerging family-housing policy, and a few cited Housing Delivery Test percentages were read from published-measurement summaries that should be confirmed against the source release before quotation. Political control is stated for the 2022–2026 data window; Waltham Forest and Lambeth passed to Green control and Barnet to no overall control in May 2026, after the last decision in the data. The audit locates where each restriction comes from; it does not predict the outcome of any individual application.