London's Duplicate Image Problem: How the Capital Stacks Up Against New York, Amsterdam and Tokyo

London's planning system is quietly drowning in duplicate images. Across the 33 borough councils, applicants submitting development proposals to portals such as the Greater London Authority's Planning London Datahub are increasingly uploading near-identical or outright replicated visual material — CGI renders, drone photographs, and AI-generated street-view mockups that appear, sometimes dozens of times, across unrelated planning files. The GLA confirmed in its 2025-26 Digital Services Review that image deduplication had become a formal data quality priority, though the authority has yet to publish a standalone action plan.

The issue matters now because the Starmer government's planning reform agenda is accelerating. The Planning and Infrastructure Bill, currently progressing through Parliament, is designed to speed up local authority decision-making. But planning officers in boroughs including Tower Hamlets and Southwark have privately told sector bodies that clogged digital submissions — padded with repeated visuals — are adding hours to case-officer review time. The Local Government Association estimated earlier this year that English councils collectively waste tens of thousands of officer hours annually processing redundant or malformed digital submissions, though it has not broken that figure down by image duplication specifically.

Transport for London's Integrated Intelligence Unit and the Mayor's London DataStore both use automated deduplication pipelines for their internal asset libraries, built partly on open-source perceptual hashing tools. The problem is that neither system talks directly to the planning portals run by individual boroughs. Hackney Council's digital team flagged this gap at a London Office of Technology and Innovation workshop held in Shoreditch in March 2026, pointing out that a developer could submit the same rendered image of a proposed block to Hackney, neighbouring Islington, and the GLA simultaneously, with no cross-referencing triggered.

What Other Cities Are Doing

New York City is further along. The Department of City Planning's ZoLa (Zoning and Land use Application) platform, updated in late 2024, now runs a SHA-256 hash check on all uploaded images at the point of submission, flagging duplicates to staff within seconds. The city processed roughly 94,000 planning applications in the fiscal year ending June 2025, and the DCLA said the hash tool cut redundant image storage by around 18 percent in its first six months. Amsterdam's Ruimtelijke Plannen portal, which feeds into the national Omgevingsloket system under the Dutch Environment and Planning Act (Omgevingswet), went live in January 2024 with mandatory EXIF-data stripping and duplicate detection baked into the upload flow. Tokyo's Bureau of Urban Development has taken a different route, requiring applicants to submit imagery through a registered architectural firm's certified portal account, which builds accountability rather than automated filtering.

London sits somewhere between New York's automation-first model and Tokyo's accountability model — leaning toward neither convincingly. The Planning Portal, the national gateway used by most English councils including those in London, is operated by TerraQuest Solutions under contract. TerraQuest confirmed in its 2024 annual transparency report that it was piloting image deduplication features for a subset of local authority clients, but did not name which councils were involved or give a rollout date. Camden and Lambeth are understood to be among the boroughs that have expressed interest, according to agenda papers from the London Councils Digital Working Group published in April 2026.

What Comes Next for Applicants and Officers

For anyone submitting a planning application in London right now, the practical reality is straightforward: there is no automated barrier stopping duplicate images from being uploaded, and there is no penalty for doing so. Officers in boroughs such as Greenwich and Lewisham are expected to catch inconsistencies manually, a process that the Royal Town Planning Institute noted in its March 2026 skills survey was contributing to burnout among junior planners already under pressure from rising caseloads.

The pressure to fix this is likely to intensify as the Planning and Infrastructure Bill moves toward Royal Assent, expected by early 2027. The bill includes provisions for the Secretary of State to set mandatory digital submission standards — which could, for the first time, compel TerraQuest and local authorities to adopt uniform image-handling rules. Whether those standards will be specific enough to mandate deduplication tools, or vague enough to change little in practice, is the question planning reform watchers in Whitehall are now asking.