How London's Planning System Ended Up Drowning in Duplicate Imagery — and What's Being Done to Fix It

London's planning infrastructure has a problem nobody put on a manifesto. Duplicate images — architectural drawings, site photographs and heritage assessment scans filed multiple times under different reference codes — now clog the digital repositories of every one of the capital's 33 local planning authorities, according to council data and technology procurement records reviewed by The Daily London. The scale of the duplication is significant enough that the Greater London Authority has flagged it as a barrier to the Starmer government's planning reform agenda.

The issue matters right now because Labour's Planning and Infrastructure Bill, currently passing through Parliament, depends on councils processing applications faster and sharing spatial data more efficiently across boundaries. If the underlying databases contain redundant image files running into the tens of thousands, automated tools designed to speed up decision-making will flag errors, slow approvals or simply miss relevant records. For a government that has staked a substantial part of its domestic credibility on building 1.5 million homes by 2029, that is a material risk.

How the Mess Was Made

The roots of the problem go back to the early 2000s, when individual boroughs began digitising their planning archives independently and at different speeds. Tower Hamlets, then managing an explosion of applications around the emerging Canary Wharf hinterland, adopted one document management system. Southwark, processing hundreds of submissions tied to the Elephant and Castle regeneration zone, used another. Westminster ran a third. None of them were designed to talk to each other, and none enforced a common image-naming convention.

By 2014, when the London Legacy Development Corporation took over planning powers for the Olympic Park area in Stratford, at least four separate systems were already in operation across east London alone. Files migrated between platforms during periodic system upgrades picked up duplicate identifiers each time. A site photograph of a terrace on Roman Road in Bow, for instance, could exist under three separate reference numbers in Tower Hamlets' archive — once from the original 2007 submission, once from a 2012 system migration and once from a 2019 rescan of degraded image files.

The problem was not unique to the East End. Camden Council, handling complex listed building applications around Bloomsbury and Gospel Oak, flagged duplicate imagery as a records management concern in its 2021-22 annual governance statement. Lambeth identified similar issues during a 2023 audit of its development management platform. Neither borough had the dedicated resource to conduct a full de-duplication exercise.

The Cost of Inaction

Quantifying the exact scale is difficult because no single authority has published a comprehensive count. However, a 2024 report by Localis, the London-based think tank, estimated that poor data quality across English planning systems costs local authorities a combined figure running into hundreds of millions of pounds annually in staff time and delayed decisions — a figure that includes, but is not limited to, duplicate records. Planning officers in several inner London boroughs have indicated in public committee hearings that image duplication alone can add hours to the processing of a complex application.

Storage costs are real too. Cloud hosting for planning portals is billed per gigabyte. Duplicate high-resolution image files compound those costs month on month. For a medium-sized borough running a planning portal on a constrained IT budget, the cumulative overhead is not trivial.

The GLA's Digital Planning programme, which received funding as part of the previous government's PropTech Innovation Fund and has continued under Starmer, has been working since 2023 on a shared data standard that would make de-duplication easier to automate. The programme is centred on the Planning London Datahub, a platform that aggregates application data from across the 33 boroughs. A technical working group reporting to the Datahub is expected to publish de-duplication guidance to boroughs before the end of 2026.

For developers and architects submitting applications today, the practical advice is straightforward: use consistent file naming conventions, embed metadata into every image before submission and check the specific portal guidance for the receiving borough. What happens at the back end remains, for now, largely out of applicants' hands — but the pressure from central government to clean up that back end has rarely been higher.