Leeds Council's Image Archives: The Hidden Duplication Problem Nobody Has Counted — Until Now

Leeds City Council holds tens of thousands of digital images across its planning, communications and heritage systems — and a significant proportion of those files are duplicates. An ongoing review of the council's digital asset management infrastructure, begun in the first quarter of 2026, has started to put hard numbers to a problem that archivists and planning officers have long complained about informally. Early findings from the audit, which covers repositories linked to the Leeds Planning Portal and the Thoresby Society's digitised collections held at the Leeds Central Library on Calverley Street, suggest that duplicate or near-duplicate image files account for somewhere between 18 and 24 percent of total stored assets in the systems examined so far.

That range matters because storage is not free. Cloud and server hosting costs for local authorities have risen sharply across Yorkshire in recent years, and Leeds — which operates one of the largest local authority digital estates outside London — is no exception. Across West Yorkshire Combined Authority member councils, digital storage expenditure increased by roughly 31 percent between 2022 and 2025, according to figures presented to the Combined Authority's scrutiny committee in March 2026. Duplicate imagery is a direct, avoidable contributor to that overhead.

Where The Duplicates Come From

The mechanics are not complicated. Contractors submitting planning applications to the Leeds Planning Portal routinely upload the same site photographs in multiple document packages. A planning application for a residential conversion in Headingley might contain the same exterior photograph embedded in the design-and-access statement, the heritage impact assessment and the flood-risk appendix — three separate uploads, one image. Across a city that received 4,847 planning applications in the 2024/25 financial year, that accumulation becomes substantial.

The problem is compounded at the heritage end. The Leodis photographic archive, managed by Leeds Libraries and containing more than 100,000 historic images of the city, underwent a partial migration to a new content management system in late 2023. Data migration events of that kind are a well-documented trigger for duplication: files that already exist in a destination system get written again if metadata identifiers do not match precisely. Leodis staff identified approximately 2,300 probable duplicate image records following that migration, according to documentation circulated within the Leeds Libraries digital services team.

Meanwhile, the council's corporate communications team, based at Merrion House on Merrion Way, draws on a shared image library that has grown organically since the mid-2000s. No systematic deduplication has been performed on that library since 2019. The library currently holds approximately 41,000 files.

The Cost Of Doing Nothing

Deduplication is a solved technical problem. Software tools that identify identical files by hash value, and near-duplicate images by perceptual hashing algorithms, are widely available and have been deployed by NHS trusts, universities and national government departments. The Cabinet Office's Central Digital and Data Office published guidance on digital asset housekeeping in February 2025 that specifically referenced image duplication as a low-cost, high-return efficiency gain for public bodies.

Leeds City Council's own digital transformation programme, set out in a strategy document published in October 2024 under the heading Digital Leeds 2030, commits the authority to reducing redundant data holdings and improving asset discoverability across all public-facing platforms by the end of the 2026/27 financial year. The image audit currently under way is understood to be part of delivering against that commitment.

For residents and professionals who use the Leeds Planning Portal daily — architects submitting schemes for new-build developments on the South Bank regeneration zone, or community groups trying to access heritage records for streets in Chapeltown or Armley — a cleaner, faster database has practical consequences. Search results cluttered with duplicate thumbnails slow retrieval and raise the risk of errors when the wrong version of an image is cited in a formal document.

The audit is expected to produce a full report for the council's digital governance board by September 2026. If the 18-to-24-percent duplication estimate holds across the full estate, Leeds is looking at a potential reduction of between 7,000 and 10,000 redundant image files from the systems reviewed so far — and corresponding storage savings that digital officers will be expected to quantify in pounds before the next budget cycle begins.