London Councils and Archives Race to Fix Duplicate Image Crisis in Digital Planning Records

Planning officers across at least six London boroughs flagged a systemic problem this week with duplicate and incorrectly labelled images embedded in digital planning applications — a technical fault that has been quietly stalling decisions on everything from loft conversions in Lewisham to major commercial redevelopments in Southwark. The issue, which stems from automated document-scanning workflows used by local authority portals since 2023, came to a head after the Greater London Authority's planning directorate circulated an internal advisory note on 1 July urging borough planning departments to audit their active caseloads.

The timing matters. The Starmer government has staked a significant share of its political capital on accelerating planning approvals, and Housing Secretary Angela Rayner's Planning and Infrastructure Bill — currently making its way through Parliament — sets binding targets for local authorities to process applications faster. Any backlog, however technical its origin, puts councils in the uncomfortable position of missing those targets while the legislative pressure mounts.

Where the Problem Has Surfaced

Tower Hamlets Council confirmed to planning professionals this week that its online portal, which handles roughly 4,500 applications a year, had been generating duplicate image attachments when applicants uploaded files larger than 10MB through the borough's document submission system. Officers in the Whitechapel-based planning hub discovered that in some cases the same site photograph was appearing four or five times within a single application pack, inflating file sizes, slowing officer review times and, in a handful of cases, replacing the correct elevations drawing with a repeated copy of an unrelated image. Lambeth Council reported a similar pattern affecting applications submitted along the Brixton town centre regeneration corridor since late February.

The problem is not confined to one software provider. Two of the affected boroughs use Idox's Uniform planning system, while at least one runs on the Acolaid platform. Both companies are understood to be investigating, though neither has issued a public statement as of Saturday morning. The GLA advisory note stops short of naming vendors but recommends that officers manually verify image sequences in any application where the total file size exceeds 25MB.

For applicants, the practical consequence can be a formal request for additional information — known in planning parlance as a Section 5 notice — which resets the statutory eight-week determination clock. A homeowner in Forest Hill described receiving such a notice last month, only to be told the duplicate image was uploaded by the portal itself rather than by their architect. Their application clock was reset regardless.

What the Data Shows

The Planning Portal, which processes applications on behalf of English councils, published figures in May 2026 showing that image-related submission errors accounted for 11 percent of all invalid application notices issued in London during the first quarter of the year — up from 6 percent in the same period of 2025. That rise tracks almost exactly with the wider rollout of automated bulk-scanning tools that councils adopted to comply with the government's digitisation mandate, which required all London boroughs to be fully paperless by January 2024.

The GLA's advisory note, dated 1 July, recommends that borough IT teams implement a file-deduplication check at the point of upload, a step that the national Planning Portal has apparently already built into its latest release but which individual council portals running legacy software have yet to integrate. The cost of retrofitting that check varies by system, but officers familiar with the process estimate it typically requires between two and four weeks of development time.

For anyone with a live application currently sitting with a London borough, the advice from planning professionals this week is straightforward: log into your council's online portal, download your own submission, and check that the images attached match what your agent originally sent. If they do not, contact the case officer directly — by email rather than through the portal's messaging function, which in some cases routes through the same affected workflow. Do not wait for a formal invalid notice, because once that clock resets, there is no fast-track route to recover the lost weeks. The GLA has said it expects boroughs to confirm their audit status by 18 July.