The online historic mapping website Know Your Place (West of England) is a very useful resource as it can display a “comparison map” such as a tithe map overlaid on a “base map” such as the Ordnance Survey 25 inch to one mile County series map.

Unfortunately, it is not possible to determine from the Know Your Place the sheet number or date of any Ordnance Survey map displayed. However if this information is required, the two online resources described below can provide it.

1. National Library of Scotland   OS Sheet Records Viewer

The National Library of Scotland’s excellent Map Images website can display a comprehensive range of historic Ordnance Survey maps at the scale of 25 inches to the miles and at smaller scales down to 1 inch to the mile. One section of the site is the OS Sheet Records Viewer and enables the user to obtain the sheet number and dates for map scales between 1:1250 to 1:10000.

Having opened the OS Sheet Records Viewer and displayed the modern index map the user selects the required map scale the then clicks on the required location in the index map.

The records for the maps showing the location appear in a new panel on the right hand edge of the screen. Where there is more than one edition for a given scale the records are listed for each edition and give the sheet number and the dates of the initial survey (or subsequent revision) and publication.

It should be noted that it is not possible to display the corresponding map images, directly from the map records section of the website. However, map images are readily available from other parts of the site.

2. The Charles Close Society Sheetfinder

The Charles Close Society for the Study of Ordnance Survey Maps has an online facility called Sheetfinder. This displays a modern map of the UK where the user can enter a place name into a search box or double click on the location of interest on the map to set the desired location. An infobox appears at that location on the map giving the sheet number, sheet name and the dates of the initial survey or (subsequent revision) and publication for a range of Ordnance Survey maps. In addition, the sheet name is a link to the corresponding map image (if available) on the National Library of Scotland Map Images website referred to above.

Unfortunately the results are limited to the One-Inch, 1:50,000 and six-inch County series map sheets and does not include the 25-inch County series mapping. However, as the six-inch and 25-inch published maps are derived from the same survey data the survey or revision date for a 25-inch sheet will normally be the same or only a year out from the date for the corresponding six-inch sheet. The sheet number for a 25-inch map may be inferred from the sheet number for corresponding six-inch map.