London Planning Offices Race to Strip Duplicate Images From Thousands of Housing Applications This Week

London's planning system moved quickly this week to address a backlog problem that has quietly frustrated architects, developers and council officers for months: duplicate images lodged against housing and development applications are clogging the Greater London Authority's planning portal, slowing decision times and, in several cases, causing valid applications to be rejected on procedural grounds.

The issue came to a head after the Planning Inspectorate flagged in late June that a growing number of appeals were being delayed because supporting documents contained repeated or mislabelled image files. Borough planning departments across the capital have now been asked to audit live applications before a July 18 deadline set by the GLA's digital planning team.

What Happened This Week

Tower Hamlets, Southwark and Lambeth were among the boroughs to confirm this week that their officers are working through case queues to identify and remove duplicated site photographs, elevation drawings and heritage impact images. In Tower Hamlets alone, planning officers are reviewing more than 400 active applications, according to council documents published on its website Wednesday. Lambeth's planning portal listed 23 applications placed on hold pending image correction as of Thursday morning.

The problem is partly technical. London's planning portal, which sits under the Planning and Infrastructure Act 2025 framework being rolled out nationally, has a file-upload system that does not automatically flag when an identical image file is attached more than once under different document labels. A drawing submitted as both a 'proposed elevation' and a 'existing elevation' by mistake can cause automated pre-validation checks to fail, throwing an application back to the applicant queue and resetting the statutory determination clock.

For applicants with time-sensitive schemes — affordable housing blocks, permitted development conversions, even minor extensions in conservation areas — a reset clock can mean weeks of additional delay. In Bermondsey, one architect working on a mixed-use scheme on Mandela Way described the situation to trade publication AJ this week as a source of serious frustration for smaller practices that lack dedicated document managers. The GLA has not published a full count of affected applications across all 33 boroughs.

The Broader Pressure on Planning

The timing matters. The Starmer government's push to build 1.5 million homes over the current Parliament has put enormous strain on borough planning departments, which are being asked to process more applications faster while implementing new digital systems simultaneously. The Planning and Infrastructure Bill, currently passing through Parliament, is designed to accelerate decisions, but its digital components are being phased in unevenly across London's boroughs.

Camden Council's planning service, which covers one of the most active development zones in the capital including the HS2 corridor near Euston Station, confirmed this week that it had updated its applicant guidance notes to include explicit instructions on image file labelling. Islington Council published a similar notice on July 1, warning applicants that mislabelled duplicates would trigger an automatic validation failure from July 14 onwards rather than a manual review.

The GLA's digital planning unit — part of City Hall on the South Bank — is understood to be testing an automated duplicate-detection tool that would flag repeat image files at the point of upload. No launch date has been confirmed publicly.

For anyone submitting a planning application to a London borough in the coming weeks, the practical advice from borough guidance documents published this week is consistent: use unique, descriptive file names for every document, avoid uploading the same image under more than one category label, and check the validation checklist specific to each borough before hitting submit. Applicants with live applications already flagged for review should expect contact from their case officer before July 18. Those who do not hear back by that date are advised to contact their borough's duty planning officer directly rather than waiting for an automated notification.