How London's Planning System Ended Up Drowning in Duplicate Images — And What's Being Done About It

London's planning departments are sitting on a backlog of duplicate and mismatched images embedded in thousands of active applications — a technical failure that has quietly delayed decisions on housing schemes from Newham to Southwark and drawn criticism from developers who say the problem adds weeks to already strained approval timelines.

The issue matters now because the Starmer government has staked its domestic credibility on accelerating housebuilding, with Planning Minister Matthew Pennycook pushing local authorities to hit ambitious delivery targets under the revised National Planning Policy Framework. Any friction inside the digital planning stack — however unglamorous — has direct consequences for whether sites get approved and spades go in the ground.

How the Duplication Problem Took Root

The trail runs back to the early 2010s, when councils across Greater London migrated their planning registers to online portals. The Greater London Authority's Planning London Datahub, which aggregates applications from all 33 boroughs, inherited whatever those local systems uploaded. When applicants resubmitted drawings after amendments — standard practice on any medium-sized scheme — many portals lacked the logic to flag that a newer version had replaced an older one. Both stayed live, tagged with the same or near-identical metadata.

Tower Hamlets, which processes more major applications per square kilometre than almost any other London borough, flagged the duplication issue internally as far back as 2019, according to documentation published under a Freedom of Information request by planning consultancy Lichfields. By that point, the borough's portal held multiple image files for roughly one in six live applications. At Southwark Council, where the Bakerloo line extension corridor has generated sustained planning activity around Old Kent Road, officers reported spending measurable staff time manually reconciling document versions before committee hearings.

The GLA's London Plan process added another layer. When the current London Plan was adopted in March 2021, applicants were required to submit design documentation in updated formats. Schemes that had been submitted under the previous 2016 plan and then revised to comply with the new one ended up with double sets of supporting visuals — one batch referencing old policy documents, one referencing new — sitting simultaneously on public-facing portals without clear labelling.

The Practical Cost and What Comes Next

Quantifying the delay is difficult, but the Planning Inspectorate's own data on major London appeals shows that document management disputes — including challenges over which version of a drawing represents the current scheme — contributed to procedural adjournments in at least 14 cases decided between January 2023 and December 2025. Each adjournment adds a minimum of four to six weeks to a process already averaging 29 weeks for major applications in inner London boroughs.

For smaller developers, the costs are more immediate. A mid-sized residential scheme on a site like the former industrial land off Bermondsey Street in SE1 might carry professional fees running to several thousand pounds a month during an extended pre-determination period. Duplicate image confusion, which can trigger a formal request for clarification from a case officer, extends that clock.

The Mayor's office and the Planning Advisory Service — the Local Government Association body that supports planning departments nationally — have both indicated that a technical working group is examining standardisation across London's 33 borough portals. The aim is to introduce version-control logic that flags superseded documents automatically rather than requiring officers to catch them manually. No firm implementation date has been announced publicly.

For developers and their agents currently navigating active applications, the practical advice from planning professionals is straightforward: withdraw and resubmit superseded drawings explicitly rather than simply uploading replacements, and request written confirmation from the case officer that the older versions have been removed from the live register. At Lambeth Council, where the planning portal is managed through the Idox Uniform system used by the majority of London boroughs, officers have discretion to archive superseded files — but only if formally asked to do so. That request costs nothing and can prevent an ambiguous document record from becoming a problem at committee.