Duplicate Images in Planning Applications: What Officials, Experts and Key Figures Are Saying

Planning officers across several London boroughs are raising concerns about a persistent and largely undiscussed problem: duplicate and incorrectly labelled images embedded in housing and development applications, which experts say are distorting assessment processes and, in some cases, delaying approvals by weeks. The issue has come into sharper focus this summer as the Starmer government pushes its Planning and Infrastructure Bill through Parliament, promising to speed up the system dramatically.

The problem is not abstract. When a developer submits a planning pack for, say, a mixed-use scheme on Old Street or a residential conversion in Lewisham, the digital document bundles routinely contain duplicate photographs — sometimes dozens of identical site images filed under different reference numbers. Officers then spend time cross-checking records manually, a bottleneck that undermines the efficiency gains the government is promising.

What Officers and Digital Specialists Are Saying

Professionals working inside the system describe the duplicate image problem as a symptom of fragmented software infrastructure rather than developer bad faith. Several London boroughs, including Hackney and Southwark, use planning portals built on legacy database architecture that does not automatically flag repeated file submissions. Applicants uploading images through the Planning Portal — the national system managed by the Planning Portal consortium and used by the majority of English councils — can re-upload the same file with a different filename, and the system logs it as a distinct document.

Digital planning specialists point to the 2023 Department for Levelling Up, Housing and Communities review of the Planning Portal's technical infrastructure, which identified document duplication as one of several data-quality issues affecting case management. The portal processed more than 400,000 applications in England in 2023, according to figures published by the Planning Portal consortium, meaning even a small percentage of duplicate-image cases represents a significant administrative drag across the country.

At the Greater London Authority, officers handling strategic applications — those above the threshold referred to the Mayor's office for sign-off — have begun flagging image duplication as part of a broader push for standardised digital submissions. The GLA's planning directorate has encouraged applicants submitting schemes to the London Plan 2021 framework to follow image-naming protocols, though these remain guidance rather than enforceable requirements.

The Pressure From Westminster

The timing matters. The Planning and Infrastructure Bill, currently before the House of Commons, includes provisions aimed at digitising the application process end-to-end by 2028. Housing minister Matthew Pennycook has spoken publicly about cutting decision times for major applications. But critics within local government argue that digitisation targets will mean nothing if the underlying data — including images — arrives in the system in a chaotic state.

Tower Hamlets Council, which processed roughly 3,800 planning applications in the 2024-25 financial year according to its published performance data, has been piloting an image-deduplication check at the validation stage. Officers there have been working since January 2026 with a small tech team to flag files where hash values — a digital fingerprint — match exactly, triggering an automatic query back to the applicant before the case is formally registered.

The approach is modest in scope but has attracted attention from planning departments in Islington and Lambeth, both of which face significant application backlogs. A duplicate image in a major residential scheme may seem trivial, but when an officer is working through a 200-page PDF bundle for a 150-unit development near Elephant and Castle, redundant files extend validation time measurably.

For developers, architects and planning consultants operating in London, the practical advice from legal specialists is straightforward: audit image files before submission, use consistent naming conventions tied to drawing numbers, and verify that the Planning Portal's own upload confirmation screen shows distinct file sizes for each document. Firms submitting large applications to boroughs such as Camden or Greenwich are increasingly using pre-submission checklists that include a deduplication step.

The GLA has indicated it will publish updated digital submission guidance for applicants later this year, with a target date in the autumn 2026 programme. Whether boroughs follow suit — and how quickly — will depend in part on whether the Planning and Infrastructure Bill passes in a form that mandates, rather than merely encourages, standardised digital data across the English planning system.