Data methodology
Every number on this platform comes from public records. This page explains exactly where the data comes from, how it is filtered, and what the figures mean.
On this page
Application-level data is drawn from the statutory planning registers of all 33 London local planning authorities. Each register is a public record, maintained under the Town and Country Planning (Development Management Procedure) (England) Order 2015.
Appeal outcome data is sourced from the Planning Inspectorate's published decision records. These cover all appeals decided under section 78 of the Town and Country Planning Act 1990 — the standard route for refused applications.
Policy data for the Westminster analysis covers all 901 policies in the Westminster City Plan 2019–2040, cross-referenced against appeal decision letters to identify which policies inspectors uphold and which they routinely overturn.
A development is classified as a major residential scheme when it proposes 10 or more dwellings, or where the site area is 0.5 hectares or more and the number of dwellings is not specified. This follows the definition in the Town and Country Planning (Development Management Procedure) (England) Order 2015, Schedule 4.
The following are excluded from refusal rate calculations: householder applications (extensions, loft conversions), change of use applications, prior approval notifications, applications for consent under listed building or conservation area provisions, non-material amendments, and applications for minor residential schemes (under 10 dwellings). This is by design — mixing application types would make borough comparisons meaningless.
Householder applications account for the majority of planning decisions nationally, and their refusal rates behave very differently to major schemes. A borough that refuses a high proportion of extensions may approve large housing developments readily, and vice versa. Filtering to major residential isolates the decision-making behaviour that is most relevant to developers.
Refusal rate = (refused decisions ÷ total decided applications) × 100, where both numerator and denominator are filtered to major residential schemes within the relevant date range. Withdrawn applications are excluded from both.
The default view covers 2010 to present. This captures a full cycle of market conditions and planning policy changes, including the effects of the National Planning Policy Framework (introduced 2012), subsequent revisions, and the post-2020 recovery. Trend views are available year-by-year from 2010.
We use decision date rather than application date. This reflects the actual output of the planning system in a given period and avoids distortion from applications that were submitted in one year but decided in another.
An appeal is counted as overturned when the Planning Inspectorate allows an appeal against a refusal — meaning the inspector disagreed with the council's decision. The overturn rate for a borough is: allowed appeals ÷ total decided appeals (excluding withdrawn appeals).
Inspector-level data tracks the outcome of every appeal assigned to each inspector. Rates are not adjusted for appeal type or scheme size — these are raw overturn rates. We present them with decision counts so users can assess statistical reliability: an inspector with 3 decisions has a less meaningful rate than one with 80.
Our appeal dataset covers 20,000+ Planning Inspectorate decisions for London, from 2010 to present. Not all appeal types are included: we focus on section 78 appeals (refused applications and non-determination). Enforcement appeals, lawful development certificate appeals, and other appeal types are excluded.
Each Westminster appeal decision letter is parsed to identify which local plan policies the council cited as reasons for refusal, and whether the inspector upheld or dismissed those reasons. A policy is marked as "challenged" when it appears in a refusal reason that the appellant contested. The challenge rate is: appeals where the policy was overturned ÷ total appeals where the policy was cited.
The policy cross-reference currently covers Westminster only. Westminster was chosen as the first borough because it has one of the most actively contested planning environments in London, a large and well-structured local plan, and a high volume of appeal decisions. Other boroughs will be added as data is validated.
A high overturn rate on a policy (e.g. 80% allowed) means that when inspectors are asked to rule on that policy ground, they usually side with the appellant. This does not mean the policy is unlawful — it means it has historically been a weak ground for refusal when challenged. A low overturn rate (e.g. 10% allowed) means inspectors consistently uphold that policy when councils rely on it.
London planning registers are maintained independently by each LPA and vary in completeness and classification accuracy. Some authorities are inconsistent in how they categorise application types. We validate data by spot-checking against published decision notices, but minor errors in borough totals are possible.
Planning Inspectorate decision records typically appear 4–8 weeks after the decision is issued. Our appeal data is therefore not fully real-time for the most recent period.
This platform presents historical records from the public planning system. Refusal rates describe what has happened; they do not predict what will happen on any specific application. Planning decisions depend on the specific proposal, the site, the officer, the political context, and the policy environment at the time of decision — none of which is captured in an aggregate rate.
Data is updated monthly. The date of the last update is shown on all data views.
Development Intent Ltd. Methodology v1 · Last updated March 2026.