London's Planning System Wakes Up to the Duplicate Image Problem: What Officials, Experts and Key Figures Are Saying

Planning applications submitted to London's 33 borough councils contain tens of thousands of duplicate design images, according to digital governance specialists who have been pressing Transport for London, the Greater London Authority and individual planning departments to clean up their public-facing document repositories. The problem, dismissed for years as a filing quirk, is now being framed as a genuine obstacle to public participation in the planning process — and to the government's own housing delivery targets.

The timing matters. Keir Starmer's Labour government has staked a significant part of its domestic agenda on accelerating housebuilding, with planning reform at the centre of that push. The Planning and Infrastructure Bill, currently making its way through Parliament, is designed to speed up approvals. But critics argue that cluttered, duplicated document sets on portals like the London Development Database make it harder for residents, campaign groups and ward councillors to scrutinise proposals efficiently — adding friction to a system that ministers say they want to streamline.

What the Experts Are Actually Saying

Digital archivists at University College London's Bartlett School of Planning have been tracking the issue for roughly 18 months. Their working position — outlined in a February 2026 seminar at 22 Gordon Street — is that duplicate imagery is not merely a storage inconvenience but a transparency failure. When an application for, say, a mixed-use tower in Stratford or a permitted development conversion in Peckham runs to 400 uploaded files, many of them identical floor-plan images submitted multiple times in error, the practical effect is to bury the substantive documentation. Objectors waste time; officers waste time; the public record becomes unreliable.

The Open Planning Project, a London-based civic technology group operating out of offices near Borough Market, has been building tools to flag near-duplicate images automatically using perceptual hashing — a technique that generates a compact fingerprint for each image and compares it against others in the same application. Their pilot, run across a sample of 1,200 applications from Southwark and Tower Hamlets during the first quarter of 2026, found that roughly 23 percent of uploaded image files were either exact duplicates or near-identical variants of another file in the same submission. That figure, if it holds across the full London Development Database, would represent a substantial slice of the storage and indexing burden borne by borough IT budgets.

City Hall's digital team has acknowledged the issue in internal planning technology working groups, though the GLA has not yet published a formal policy position. Sadiq Khan's planning directorate is understood to be reviewing whether the London Development Database's submission rules should be updated to include automated pre-upload deduplication checks — a step that Hackney Council piloted briefly in late 2024 before pausing the trial pending broader London-wide coordination.

What Happens Next — and What It Will Cost

The practical path forward, according to those working closest to the problem, runs through two parallel tracks. First, the boroughs need updated submission guidance that explicitly prohibits duplicate file uploads and imposes file-naming conventions rigorous enough for automated checking. Second, the back-end infrastructure of the Planning Portal — operated nationally by a consortium including the Ministry of Housing, Communities and Local Government — would need to support real-time deduplication at the point of upload rather than leaving the clean-up to individual councils after the fact.

Neither track is free. Estimates circulating among London borough planning IT leads put the cost of a borough-level deduplication retrofit at between £40,000 and £120,000 per council, depending on the age of their document management system. Across 33 boroughs, that arithmetic becomes uncomfortable, particularly given the local government funding pressures that have already forced several councils — including Croydon — into exceptional financial support arrangements in recent years.

For residents trying to engage with planning decisions on streets like Rathbone Place in Fitzrovia or along the Old Kent Road corridor, where large regeneration schemes are already generating dense application sets, the message from practitioners is straightforward: if a document pack looks confusing and repetitive, it probably is. Cross-referencing file names manually against the application index remains the most reliable way to identify which drawings are substantively new. That is a poor workaround — but for now, it is the one available.