The Ordnance Survey National Grid system employs a two letter and six-figure grid reference to denote a location. The preferred format is:

<2-Grid letters><3-figure easting><3-figure northing>
Example: NJ518152

Grid references can be obtained from the Discover Series maps available from the Ordnance Survey.
Alternatively, it is possible to obtain or estimate the grid reference by following the Ordnance Survey Get a Map link. Once on the site click on the pink "Get-a-Map" link and use the cross hairs to locate the position you require. The grid reference of the cursor position is displayed beneath the map. To learn more on how to use the Ordnance Survey National Grid system please click here.

If you are unsure of your grid reference reading, please indicate this in the comment field on the sightings form.