London Councils Race to Purge Duplicate Images From Planning Portals This Week

Several London boroughs moved this week to strip thousands of duplicate images from their public planning portals, following guidance issued by the Planning Inspectorate that flagged data-quality failures as a risk to legal challenges against development decisions. The clean-up effort, which accelerated after a deadline set for 30 June 2026, affects planning applications stretching back nearly a decade on systems used by councils including Tower Hamlets, Southwark, and Lewisham.

The timing matters. Keir Starmer's government has staked a significant part of its domestic agenda on accelerating housebuilding through planning reform, and the credibility of that programme rests partly on local planning portals being accurate, searchable, and legally defensible. Duplicate image files — often created when applicants resubmit documents or when legacy systems migrated data — can obscure the official version of a submitted plan, slow down case officer reviews, and, in the worst cases, be cited by objectors as procedural errors during appeals.

At Tower Hamlets, where the authority processed more than 4,200 planning applications in 2024-25 according to its own published performance data, staff have been working through a backlog on the Northgate Public Access system since Monday. Southwark Council, whose portal covers major regeneration zones including the Old Kent Road Opportunity Area, confirmed it is auditing documents submitted since 2018. The London Legacy Development Corporation, which oversees planning in the Queen Elizabeth Olympic Park area in Stratford, is separately reviewing its own document management workflow after the same guidance was circulated.

What Is Actually Going Wrong

The technical problem is less dramatic than it sounds but genuinely consequential. When a planning agent uploads a revised site plan, some portal software creates a new image record rather than replacing the old one, leaving both versions live and labelled identically. A case officer searching for the current floor plan may open the superseded version. Multiply that across thousands of applications and the cumulative risk to decision quality grows substantially.

The issue came into sharper focus earlier this year when a planning appeal in Lambeth — relating to a mixed-use scheme on Coldharbour Lane — was complicated by precisely this kind of document duplication, according to publicly available appeal correspondence published on the Planning Inspectorate's website. No decision was overturned solely on that basis, but inspectors noted the portal records were not in good order, a finding that cost the authority time and legal resource.

The Local Government Association has been pressing suppliers of planning software — including Idox, which powers portals for a large share of English councils — to build automatic deduplication into their systems. Idox declined to provide a comment for this article by the time of publication. Several boroughs are currently running manual audits rather than waiting for a software fix, a process one Hackney planning officer described in a public webinar last month as reviewing more than 12,000 individual image records by hand.

What Comes Next for Residents and Applicants

For Londoners with live planning applications, the practical advice from borough communications teams is consistent: if you submitted documents before July 2026 and want to confirm which version is the current one on the register, contact the case officer directly by email with your application reference number rather than relying solely on the portal display. Most boroughs are responding to those queries within five working days, though Tower Hamlets has warned of slightly longer turnaround times through mid-July due to the volume of the audit work.

Applicants lodging new submissions from this week onward are being asked by several boroughs to name files consistently and avoid resubmitting existing documents under new filenames — a small change that reduces the chance of duplicate records being created in the first place. The Greater London Authority's Digital Planning team has said it plans to publish updated guidance for planning agents before the end of July 2026.

The broader significance is straightforward. With large schemes on the Old Kent Road, in Barking Riverside, and around Euston set to move through the planning system over the next 18 months, the accuracy of portal records is not a minor administrative detail. It is a legal foundation. Getting the data right now is considerably cheaper than fighting appeals over it later.