How London's Planning Departments Got Buried Under Duplicate Images — and Why It's Now a Crisis

London's 33 borough councils are sitting on a sprawling, largely invisible backlog problem. Across planning portals from Newham to Richmond, duplicate image files — the same architectural drawing submitted two, three, sometimes five times under different file names — have accumulated for years inside case management systems, consuming server storage, slowing document retrieval, and, most critically, delaying the processing of planning applications that Keir Starmer's government needs approved at scale to hit its national housebuilding targets.

The problem did not arrive overnight. It is the accumulated result of a decade of incremental digitisation without standardisation, and it has become politically urgent in 2026 because housing delivery cannot wait.

How the Duplication Built Up

The roots trace back to roughly 2013, when most London boroughs began migrating away from paper-based planning files toward digital document management. The Greater London Authority pushed the transition, and the Planning Portal — the national system administered by Planning Portal Ltd — became the default submission gateway. But individual boroughs retained their own back-end case management software. Idox Group's Uniform platform dominates, used by roughly two thirds of English local authorities, but integration between the national front-end portal and local back-end systems was never seamless.

When applicants submitted revised drawings — a common occurrence on any project — the new versions landed alongside the originals in the case file rather than replacing them. Automated versioning tools existed but were rarely switched on or properly configured. By 2019, a review commissioned by the London Legacy Development Corporation, which oversees planning across the Queen Elizabeth Olympic Park area in Stratford, found that individual major application files routinely contained upwards of 400 documents, with meaningful duplication rates running above 30 percent on complex residential schemes.

Then came the pandemic. Between March 2020 and June 2021, the volume of digital planning submissions across England rose sharply as site visits were replaced by additional drawing packages. Councils such as Tower Hamlets and Southwark — both processing significant flatted development pipelines along the Thames — saw their document backlogs expand faster than staff could triage them. Remote working also made it harder for case officers to cross-reference files informally, the way a physical paper pile in an office once allowed.

Why It Matters Right Now

The Levelling-Up and Regeneration Act 2023 placed new duties on councils to publish planning decisions within statutory timeframes, and the current Labour government has tied further devolution funding to performance metrics that include decision speed. Sadiq Khan's London Plan target of 52,000 new homes per year across the capital remains consistently unmet. Slow case processing is one measurable drag on that figure.

The Mayor's Planning team at City Hall published figures in its 2025 London Development Database annual report showing that the average time to determine a major application across London boroughs was 28.4 weeks — well above the statutory 13-week benchmark. That figure covers all causes of delay, but document management inefficiency, including the time officers spend navigating bloated file structures, is cited by borough planning departments as a consistent operational burden.

Hackney Council began piloting an automated deduplication tool developed with TPXimpact, a digital public services consultancy with offices in Whitechapel, in late 2024. Early results presented internally suggested the pilot reduced average document retrieval time on test case files by around 40 percent, though the tool has not yet been rolled out beyond the trial. The London Borough of Waltham Forest separately tendered in March 2026 for a document management review covering its planning and licensing functions, with responses due by the end of that month.

For applicants, the practical consequences are tangible. Developers working on schemes along the Old Kent Road regeneration corridor in Southwark report that even straightforward pre-application queries can stall for weeks when case officers cannot quickly locate the correct version of a submitted drawing amid a cluttered file.

What happens next depends partly on whether City Hall and the Ministry of Housing, Communities and Local Government move to mandate a single versioning standard across English planning portals — something officials have discussed but not yet legislated. Boroughs waiting for central guidance are advised, in the meantime, to audit existing case files for duplication before the next wave of applications linked to the government's accelerated housebuilding programme arrives later this year.