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Ordnance Survey digital mapping

Ordnance Survey and Ordnance Survey Northern Ireland have both moved to digital-only format for large-scale mapping. The British Library receives annual 'snapshots' of this data from these two UK national mapping agencies. 

The British Library maintains its archive of large-scale mapping of the nation in digital format, since 1998 for Ordnance Survey (OS) and 2004 for OS Northern Ireland (OSNI). These geospatial databases are voluntarily deposited with all of the UK Legal Deposit Libraries (LDL) annually.

OS Viewer screenshot

Screenshot of OS Viewer depicting comparison view of the same area in 1998 and 2008. ©Crown Copyright. Reproduced by permission of Ordnance Survey®


The digital maps may be viewed in LDL reading rooms using mapping applications designed specifically for this set of historical and current OS and OSNI digital data. In the British Library, it is available on the public terminal located closest to the Enquiry Desk in the Maps Reading Room. The web application is launched via the link "Ordnance Survey digital data" in the Library's listing of Electronic resources.


Color, printed extracts of A4 size may be taken by readers within the constraints of fair dealing and uses outlined by OS. Prints can be made at any of the source scales, ie 1:1,250 for urban areas, 1:2,500 for rural areas and 1:10,000 for moorland. Cost of printing adheres to wider library charges.

Deposit of OS digital data

The six UK LDLs began acquiring Ordnance Survey's Land-Line™, their initial electronic mapping data product in NTF format, in 1998. Keeping pace with technological advancements in geospatial data production and management, Ordnance Survey replaced that product with a feature-based, GML-based mapping product, OS MasterMap™, in 2006. The born-digital cartographic datasets embody the cutting edge of geographic technology and make OS a pioneer in national mapping.

Ordnance Survey MasterMap™ digital map data contains numerous layers when purchased commercially, but the LDLs receive two layers: Topography and ITN. The Topography Layer of seamless, color digital mapping identifies and datestamps each feature on the landscape uniquely, and includes land area classifications; buildings; roads, tracks and paths; rail; water; terrain and height; heritage and antiquities; structures; and administrative boundaries. The Integrated Transport Network Layer offers a detailed digital map for Great Britain 's road structure and classifications. While the Address and Imagery layers of OSMM are not deposited, the LandForm PROFILE dataset, surveyed at 1:10,000, provides contour lines and height information.

Information on printed large scale OS mapping (ie pre-1990s) at the British Library can be found on our pages for Large Scale Ordnance Survey maps of Great Britain in the Map Library.

Deposit of OSNI digital data

The six UK Legal Deposit Libraries began acquiring Ordnance Survey Northern Ireland digital large-scale mapping data in 2004. Like OS data, it is deposited as an annual snapshot, and is available in the Maps Reading Room through a similar viewer and according to the same restrictions.

The most current large-scale mapping is available through the Land & Property Services’ online map tool, Geohub NI.