London's Duplicate Image Problem: The Key Decisions Ahead for the Capital's Planning Records

London's 33 borough planning departments are sitting on a quiet but consequential mess. Tens of thousands of planning application files held across local authority systems contain duplicate, mislabelled, or incorrectly assigned images — ranging from site photographs filed against the wrong address to architectural drawings duplicated across multiple case records. The problem, long acknowledged inside council IT teams, has become urgent now that the Ministry of Housing, Communities and Local Government has set a hard deadline of April 2027 for all English planning authorities to migrate their records onto the new Planning Data Platform.

The timing matters. The Labour government under Keir Starmer has staked significant political capital on planning reform as the engine of its housebuilding programme, targeting 1.5 million new homes by 2029. Inaccurate or duplicated records do not just create administrative headaches — they can invalidate enforcement decisions, complicate appeals to the Planning Inspectorate, and in some cases leave legal ambiguity over whether a consented scheme was properly documented. For a city generating roughly 70,000 planning decisions a year, the margin for error is thin.

Where the Problem Is Concentrated

The scale varies sharply by borough. Authorities that digitalised early — Tower Hamlets, which moved to a fully electronic casework system in 2019, and Southwark, which completed a document management overhaul in 2021 — report relatively clean image libraries. The harder cases are concentrated in boroughs that still operated hybrid paper-and-digital systems into the early 2020s. Havering, Bromley, and Enfield have each flagged data quality concerns in internal IT governance reports reviewed as part of broader Local Digital Fund assessments.

The practical consequences show up in places like the Old Street and Shoreditch Opportunity Area, where a cluster of overlapping major applications filed between 2018 and 2022 has left some case files carrying duplicate elevation drawings from adjacent schemes. Islington Council's planning portal, which serves the northern end of that corridor, has been running a targeted image audit since January 2026. Similar exercises are underway at Lambeth Council for applications related to the Nine Elms regeneration zone, where more than 400 live or recently determined applications involve sites in close proximity and documents have migrated across at least three different software platforms since 2015.

What Comes Next — and Who Decides

The immediate fork in the road is a build-versus-buy question. Boroughs can commission bespoke deduplication software, contract with one of the specialist GovTech firms already operating in the local authority market, or apply for support through the Department for Levelling Up's successor planning digitalisation grants — a pot that in its most recent round, covering the 2025-26 financial year, distributed just over £14 million across English authorities.

The Greater London Authority has a coordinating role here that it has not yet fully exercised. The GLA's Planning and Development team has convened two working groups since March 2026, but borough representatives at those sessions have described the process as consultative rather than directive. Without a common deduplication standard agreed at the GLA level, boroughs risk producing clean data in incompatible formats — solving one problem while creating another upstream.

The Planning Inspectorate, which handles appeals from across England and Wales from its base in Bristol, has separately signalled that from January 2027 it will expect digitally submitted appeal bundles to meet new image integrity standards. That effectively moves the operative deadline six months earlier than the official April 2027 platform migration date for any authority whose casework generates significant appeal traffic — which, in London, means most of them.

The decisions that land on borough heads of planning over the next three months are concrete: which vendor or method to use, how to prioritise which case files to clean first, and whether to do the work in-house or pool resources with neighbouring boroughs. The London Borough of Hackney and Islington have already held preliminary talks about a shared procurement exercise, which could reduce per-borough costs. For smaller authorities with fewer planning staff, collaboration may not just be sensible — it may be the only financially realistic path before the clock runs out.