London's Planning System Is Drowning in Duplicate Images — Here's What Officials and Experts Want Done About It

London's overstretched planning departments are losing weeks of processing time each year to a problem that sounds mundane but carries real bureaucratic cost: duplicate images embedded in planning applications. Officers across at least a dozen boroughs have flagged the issue to the Greater London Authority, arguing that redundant document uploads — sometimes running to hundreds of near-identical site photographs in a single major application — are slowing validation queues at a moment when the government's housing targets make speed essential.

The Starmer government has staked a significant portion of its domestic programme on accelerating planning decisions. The Planning and Infrastructure Bill, currently progressing through Parliament, sets out ambitions to cut the average major application turnaround time and increase housing starts across England. Against that backdrop, what might look like a technical document-management headache is drawing attention from borough planners, GLA digital leads, and academic specialists who argue the problem compounds delays that are already politically embarrassing.

What Officers and Specialists Are Saying

Planning officers at Southwark Council and Hackney Council — two boroughs among the busiest for major residential applications in inner London — have separately raised concerns in GLA working group sessions this year about the volume of duplicate material arriving with large submissions. The core complaint is consistent: applicants and their consultants, often submitting through the Planning Portal, routinely upload the same image file multiple times under different document labels, or attach identical site photographs to multiple supporting reports. Validation officers must open and cross-check each file before an application can be registered, a manual process that no current Portal functionality automates away.

Digital planning specialists at Future Cities Catapult, based in Clerkenwell, have been pressing for machine-learning-based deduplication tools to be integrated into the national Planning Portal infrastructure since at least 2024. The argument is straightforward: if the Portal can flag duplicate files at the point of upload, officers never have to handle them. The technical barrier is not especially high — consumer cloud storage services have offered automatic duplicate detection for years — but procurement and governance processes within local government move slowly, and no borough has yet deployed such a tool at scale.

Academics at University College London's Bartlett School of Planning have pointed to the broader pattern. Research published by the Bartlett in 2025 found that validation delays account for a disproportionate share of total processing time on major applications in London, with some submissions spending more than eight weeks in pre-registration checking before a planning officer ever reads the substance of the case. Duplicate documents are not the sole cause, but they form part of a cluster of avoidable administrative errors that cumulatively add weeks to timelines.

Pressure Builds as Housing Targets Loom

Mayor Sadiq Khan's London Plan sets a target of 52,000 new homes per year across the capital. Delivery has consistently fallen short of that figure, and the GLA's own monitoring data shows planning delay — rather than land availability — as one of the variables boroughs most frequently cite when explaining shortfalls. That gives the duplicate-image question a political edge it might otherwise lack.

The Planning Portal, operated by TerraQuest Solutions under contract, handles the vast majority of London's application submissions. A national upgrade programme announced in late 2024 promised improved document management, but borough officers say they have yet to see material changes to how duplicates are handled during upload or validation.

For applicants — particularly smaller developers working on schemes in neighbourhoods such as Bermondsey or Walthamstow rather than the large consultancies with dedicated document-control teams — the practical advice from planning agents is blunt: audit your image libraries before submission, use a single master document for site photographs and reference it consistently across reports, and check file names to ensure the Portal does not treat separate uploads of the same JPEG as distinct documents. Boroughs including Tower Hamlets now include explicit guidance on this point in their pre-application checklist, published on the council's planning pages.

Whether the Planning Portal's next development cycle, expected to deliver updates before the end of 2026, will address deduplication at source remains the central question for the officers and specialists pushing for change. For now, the workaround is human, slow, and increasingly hard to justify.