How London's Planning System Ended Up Drowning in Duplicate Images — and Why It Finally Has to Change

Walk into the public reading room at any of London's 33 borough planning departments and ask to see a major application file from 2019. Chances are you will find the same site photograph submitted four, five, sometimes nine times under different document reference numbers. The problem has a name inside planning circles: duplicate image replacement — the practice of resubmitting identical or near-identical images to satisfy checklist requirements, pad document counts, or correct earlier mislabelling without withdrawing the original upload. It sounds trivial. The consequences for transparency and processing speed are not.

The issue matters acutely right now because the Labour government's Planning and Infrastructure Bill, introduced to Parliament in spring 2025, is pushing every English local authority toward a faster, more digitised approvals system. For London, where the Mayor's office has set a target of 88,000 new homes a year under the London Plan, any systemic inefficiency in document management directly delays the pipeline. When planning officers at a single borough — Tower Hamlets, say, or Southwark — spend time reconciling duplicate records, that is time not spent assessing whether a scheme on Old Kent Road actually meets fire safety or affordable housing thresholds.

How the Document Pile-Up Happened

The roots of the problem go back to the early 2010s, when boroughs began migrating from paper files to online portals, most of them built on the Idox Public Access platform. The software allowed applicants to upload documents at any stage of a live application. There was no automatic deduplication. An architect submitting revised drawings of a Bermondsey warehouse conversion could upload the corrected PDF while leaving the original version live — and frequently did, because removing the old file required a formal request to the case officer, who was already overloaded.

By 2017, the Greater London Authority's own monitoring of strategic applications — those it reviews jointly with boroughs — flagged that large schemes were regularly arriving with document registers running to 200 or more entries, a significant proportion of which were superseded versions of the same drawing. The GLA has no statutory power to compel boroughs to clean their registers, so the issue persisted. The Planning Portal, which handles national submissions, introduced a duplicate-detection flag for new uploads in 2021, but legacy records and borough-specific portals remained untouched.

Camden's planning register, publicly searchable on the council's website, illustrates the scale on a single high-profile scheme. The proposed mixed-use development at Euston station's western edge accumulated over 340 uploaded documents by early 2024, according to the public register — a figure that planning consultants working in the area have described privately as far exceeding what a case officer could reasonably cross-reference. Across the river, Lambeth Council's 2023 annual planning performance report noted that administrative processing time per application had risen, with document management cited among the contributing factors, though the report did not publish a specific figure attributable to duplicates alone.

What Comes Next for London's Boroughs

The Planning and Infrastructure Bill creates a new duty on local planning authorities to maintain accessible, accurate digital registers. Secondary regulations expected in late 2026 are anticipated to set minimum standards for document naming and version control — effectively forcing boroughs to implement the kind of deduplication protocols that should have been mandatory from the start. The Planning Portal has already begun piloting an automated replacement workflow with a cohort of councils, though neither it nor the Ministry of Housing has published the list of pilot authorities.

For developers, the practical advice from planning lawyers in the City of London and along the South Bank is consistent: audit your own submissions now. If a live application carries duplicate images, file a formal written request to the case officer asking them to mark superseded documents as such. It creates a paper trail and, under the new digital standards regime, positions the applicant favourably if disputes arise over what version of a drawing was valid at the point of decision. The era of stuffed document registers may be ending. Getting there has taken the better part of a decade.