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This help page explains the file names given to the historic map data which you can download from Historic Digimap.

File name prefixes

There are 3 types of file name prefix (prefix.tif, e.g.34009011.tif), associated with the 3 different types of map images that are available:

  • pre 1945 County Series original map sheets;
  • pre 1945 County Series map tiles “cookie cut” to the contemporary National Grid;
  • post 1945 National Grid map sheets.

File name suffixes

There are 3 types of file name suffix (filename.suffix, e.g. 34009011.tif), associated with the different types of files which are downloaded:

  • TIF: image files
  • TFW: ESRI GIS world files
  • TAB: MapInfo GIS world files

These file name prefixes and suffixes are described in the following sections.

County Series Original Map Sheet Names

The County Series Surveys carried out before the Second World War were not National Surveys or projected to the National Grid as with all modern Ordnance Survey mapping. Each County (or sometimes groups of neighbouring Counties) were surveyed separately with their own survey origin and sheet lines using the Casini Projection.

Consequently the way the County Series maps were named is different from the naming conventions used for all contemporary Ordnance Survey maps. The naming conventions used for the original maps are used by Landmark Information Group as the basis for the associated data files available for download via Historic Digimap.

Naming convention

County Series Original Map Sheet data files are named to the following convention:

Example: 34009011

  • The first 2 digits refer to the County: 34 = Surrey (see table below for a list of County Codes)
  • The next 3 digits refer to the Block Number: 009 = Block 9
  • The next 2 digits refer to the Sheet Number: 01 = Sheet 1
  • The final digit refers to the Edition: 1 = First Edition

In the case of 1:10,560 maps the sheet number is replaced by one of the following: NW, NE, SW, SE, or 00, depending on it being a quarter or full sheet.

Ignoring the first two and the last digit, of each file name, will leave you with the original OS Map Name, e.g.:

file name 34009011 becomes 009/01 (1:2500 County Series Map Sheet) file name 34009NE1 becomes 009/NE (1:10,560 County Series Map Sheet)

County Codes Used by Landmark in County Series Map Sheet Names

01 Bedfordshire 02 Berkshire 03 Buckinghamshire 04 Cambridgeshire & Isle of Ely 05 Cheshire 06 Cornwall & Isles of Scilly 07 Cumberland 08 Derbyshire 09 Devon 10 Dorset 11 Durham 12 Essex 13 Gloustershire 14 Hampshire &Isle of Whight 15 Herefordshire 16 Hertfordshire 17 Huntingdonshire 18 Kent 19 Lancashire and Furness 20 Leicestershire 21 Lincolnshire 22 London 23 Middlesex 24 Norfolk 25 Northamptonshire 26 Northumberland 27 Nottinghamshire 28 Oxfordshire 29 Rutland 30 Shropshire 31 Somerset 32 Staffordshire 33 Suffolk 34 Surrey 35 Sussex 36 Warwickshire 37 Westmorland 38 Wiltshire 39 Worcestershire 40 Yorkshire 41 Anglesey 42 Brecknockshire 43 Caernarvonshire 44 Cardiganshire 45 Carmarthenshire 46 Denbighshire 47 Flintshire 48 Glamorganshore 49 Merionethshire 50 Monmouthshire 51 montgomeryshire 52 Pembrokeshire 53 Radnorshire 54 Aberdeenshire 55 Argyllshire 56 Ayrshire 57 Banffshire 58 Berwickshire 59 Buteshire 60 Caithness-shire 61 Clackmannanshire 62 Dumbartonshire 63 Dumfriesshire 64 Edinburghshire 65 Elginshire 66 Fifeshire 67 Forfarshire 68 Haddingtonshire 69 Inverness-shire & Skye 70 Kincardineshire 71 Kinross-shire 72 Kirkcudbrightshire 73 Lanarkshire 74 Linlithgowshire 75 Nairnshire 76 Orkney 77 Peebleshire 78 Perthshire 79 Renfrewshire 80 Ross & Cromarty 81 Roxburghshire 82 Selkirkshire 83 Stirlingshire 84 Sutherland 85 Wigtownshire 86 Zetland (Shetland) 87 Outer Hebrides 88 Isle of Lewis 89 Isle of Skye 90 Isle of Man

County Series “Cookie Cut” National Grid Tile Names

To make the pre World War II County Series maps more easily comparable to modern National Grid maps and to allow the creation of seamless coverages in GIS, Landmark Information Group have processed the original County Series map sheets to create National Grid tiles. This was done by merging neighbouring sheets and then “cookie cutting” the original maps to an overlaid National Grid. So any one derived National Grid tile could contain parts of up to eight original County Series map sheets. More information on how this was done is available in the following Historic Digimap Help page: How Landmark digitally captured the paper historic maps.

Naming convention

The resulting National Grid “cookie cut” tiles are named using Ordnance Survey’s National Grid naming conventions with a two character prefix relating to which Historical County the data originated from (this prefix relates to those codes listed in the County Code table, above, and correspond to those used in the naming of the original map sheets).

For example: 05SJ3965

  • 05 = County Name, in this case Cheshire
  • SJ3965 = OS National Grid naming Convention

National Grid Map Sheet Tile Names

The post World War II National Grid maps and TIF data files available through Historic Digimap are named using the Ordnance Survey’s National Grid naming conventions, in the same way as all contemporary O.S. maps.

Naming convention

1:2,500 files use the following convention:

Example: TL1234

  • The first 2 digits refer to the National grid block: TL = 52
  • The next 2 digits refer to the easting: 12 = 12
  • The final 2 digits refer to the northing 34 = 34

1:1,250 files are named in the same way as the 1:2,500 files, except that one of the following is added to the end of the file name:

NW, NE, SW or SE (i.e. TL1234NE).

1:10,560 and 1:10,000 files use the following convention:

Example: TL12NEM5

  • The first 2 digits refer to the National grid block: TL = 52
  • The next digit refers to the easting: 1 = 1
  • The next digit refers to the northing: 2 = 2
  • The next 2 digits refer to the quad: NE = NE
  • The final 2 digits refer to the edition: M5 = Metric Edition 5.

The following 1:10,560 (Imperial) editions are available:

I5, I6, I7, I8

The following 1:10,000 (Metric) editions are available:

M5, M6, M7

Data Types: tif; tfw; tab

When you download map data using the Historic Digimap Download Data tab, you will get the following types of data (identified by the file prefix, e.g. TL12NEM5.TIF).

.TIF files

The TIFF map images available for download from the Download map data tab are as provided by the Landmark Information Group. All map images were supplied as CCITT Group 4 TIFF format. However, there are two varieties of Group 4 TIFF:

Banded TIFF

This type of TIFF image is read in lines, or bands, across the whole image, until the image is completely displayed. This is the most common type used for general image data.

All the post 1945 National Grid map tile images and pre 1945 County Series National Grid cookie cut images available for download from Historic Digimap are in Banded TIFF format and can be read by a wide selection of image viewing software and GIS

Tiled TIFF

This type of TIFF is read in square blocks, until the image is completely displayed. Tiled TIFF is more suitable than Banded TIFF for large images as only the blocks which will appear in the display need to be read. This is the preferred format for GIS use.

The Original County Series Map Sheet images (i.e. not those cookie cut to match the modern National Grid) available for download from Historic Digimap are in Tiled TIFF format. They can be read by GIS software (e.g. MapInfo and ESRI ArcGIS) and in some image processing software.

.TFW files

A .TFW file is a TIF World File which is used by ESRI GIS software (e.g, ArcGIS) to place the TIF map image in the correction geographic location. The TFW file should always have the same file name suffix as the TIF image it relates to (e.g. TL12NEM5.TIF and TL12NEM5.TFW) and should always be stored in the same folder as the TIF image it relates to (otherwise, ArcGIS would not find the world file when you add the TIF image, so will not know the geographic extent and position of the map image). The TFW file is a plain text file which can be opened in any text editor.

.TAB files

A .TAB file is a MAPINFO GIS Table data file which contains coordinate information used to place the TIF map image in the correction geographic location. The TAB file should always have the same file name suffix as the TIF image it relates to (e.g. TL12NEM5.TIF and TL12NEM5.TAB) and should always be stored in the same folder as the TIF image it relates to. It is essentially the MapInfo equivalent of the ESRI TFW World File.