London's Duplicate Image Problem: What Happens Next and the Key Decisions Ahead

London's property and planning system has a data integrity problem that officials can no longer quietly manage. Across borough councils, the Greater London Authority's development database, and the Land Registry's digitised records, duplicate images — photographs, site plans and scanned documents filed more than once under different reference numbers — have accumulated over years of rushed digitisation. The question now is not whether to act, but who makes the first move and on what timeline.

The issue matters today for a specific reason: the Starmer government's Planning and Infrastructure Bill, currently working through Parliament, will compel local authorities to publish fuller digital planning records as a precondition for unlocking housing delivery targets. Boroughs that cannot demonstrate clean, deduplicated data risk delays to approval pipelines at precisely the moment ministers are demanding faster sign-off on new homes. The Government set a national target of 1.5 million new homes by 2029, and London's share — roughly 88,000 a year according to the London Plan — depends on that digital infrastructure holding up.

Where the Problem Is Sharpest

Two organisations sit at the centre of the immediate decision-making: the Planning Portal, which handles digital submissions from architects and developers across England, and the London Legacy Development Corporation, which manages planning applications across the Olympic Park and Stratford area in east London. Both have acknowledged in public-facing documentation that legacy data migration from pre-2015 paper-based systems introduced duplicate image files at scale. At the LLDC alone, internal audits flagged duplicate or orphaned image assets across planning applications stretching back to the 2012 Games-era consents in Newham.

Southwark Council is another pressure point. The borough's planning department, based on Borough High Street, processes some of the highest volumes of major applications in inner London, including schemes around the Old Kent Road Opportunity Area. Duplicate images attached to overlapping planning references have, in documented cases, caused delays when case officers cannot confirm which site photograph represents the current state of a property. Those delays compound. A single confused record can stall a pre-application consultation by weeks.

The Land Registry's digital transformation programme, which moved to fully electronic title registration for the majority of London properties by 2023, also inherited duplicate scanned deeds. The Registry's own annual report for 2024-25 noted that data quality remediation remained an ongoing workstream, without specifying the number of affected records.

The Decisions That Cannot Wait

Three choices now define the next six months. First, boroughs must decide whether to run deduplication internally using existing IT budgets — already stretched after years of local government funding pressure — or to commission third-party data management firms. Contracts of this type, covering a mid-sized London borough's planning archive, have ranged between £80,000 and £250,000 depending on record volume, according to publicly available procurement notices from comparable authorities in recent years.

Second, the GLA and the Planning Portal need to agree on a shared technical standard for image metadata tagging before the Planning and Infrastructure Bill's commencement provisions kick in. Without a common standard, each borough's cleaned data will be formatted differently, making the national register the government wants functionally useless.

Third — and most consequential for developers — is the question of legal liability when a duplicate image has been used in a planning decision that has since been built out. If the wrong site photograph was attached to a consent for a scheme on, say, Lewisham's Catford Road regeneration corridor, and that error affected a neighbour's right of objection, who bears responsibility? Planning lawyers in the City have begun receiving instructions on exactly this question, though no case has yet reached the Planning Court.

Boroughs have until the end of the third quarter of 2026 to submit data readiness assessments under the Bill's secondary legislation timetable. That deadline is not aspirational — it is tied to the housing delivery grant conditions the Treasury has attached to mayoral infrastructure funding. Sadiq Khan's office has signalled it will publish guidance on acceptable deduplication standards before the summer recess ends in September. The window to get ahead of this, rather than react to it, is closing fast.