County Series Historical Maps

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Product Description:

The Ordnance Survey’s County Series historical maps were originally published between 1841 and 1893, with surveying and map publishing undertaken on a county by county basis, hence the name of the series. A series of revisions were issued up until the Second World War, after which the focus shifted to metric mapping. Surveying for the County Series maps was originally undertaken at the scale of ‘six-inches-per-mile’ (1:10,560) and from 1863 enhanced to 1:2,500 scale to meet growing demands for larger-scale mapping. The maps were based on the War Office Cassini Grid projection with separate meridians through individual origins for each county or group of counties depicted on each published paper map sheet.

A joint venture between the OS and Landmark has scanned the original paper map sheets and converted them into a digital product as a series of georeferenced raster images. The maps have been re-projected from Cassini Grid into British National Grid, the margins removed, and then mosaicked and clipped into OS national grid tile extents (each tile contains a mosaic of up to six original County Series map sheets from the same epoch, depending upon location). This means the pre-national grid historical mapping is now ready for use in geospatial systems alongside the other Jisc Geospatial Platform data products in British National Grid projection.


Product Availability:

OS County Series historic map datasets available through the Jisc geospatial data service are summarised below.

The datasets are available with the following options:

  • Epoch – the maps have been grouped into four temporal ‘epochs’ which approximately correspond to the series of revisions originally issued.  Some locations were updated more frequently, and these are identified by sub-epochs (e.g. Epoch 1-A, Epoch 1-B..).
  • Map scale – both the original 1:10,560 and the revised 1:2,500 maps are available

Please note that the geographic coverage of each particular option varies depending upon the OS’s originally surveyed and published extent.



 Epoch  Approximate Version  Map Scale(s)  Publishing Year Range
 Epoch 1  County Series Survey  1:2,500, 1:10,560  1843-1893
 Epoch 2  County Series 1st Revision  1:2,500, 1:10,560  1891-1912
 Epoch 3  County Series 2nd Revision  1:2,500, 1:10,560  1904-1939
 Epoch 4  County Series 3rd Revision  1:2,500, 1:10,560  1919-1939


Dataset Thumbnail:


Dataset Specification:

Product Name

County Series historical maps

Data Provider

Landmark (originally Ordnance Survey)


1:2,500, 1:10,560


Great Britain (various)

Data Structure





Historical Mapping


Landmark Licence

Update Frequency


Dataset Resources:

OS Historical Resources Site
Landmark Historical Maps Site
NLS County Series Index Site