What is a grid reference?
All Ordnance Survey maps are covered in a series of blue grid lines. These grid lines help you pinpoint an exact location anywhere on the map by giving a unique number known as a grid reference. The vertical lines are called eastings, as they go up in value as you travel east on the map. The horizontal lines are called northings, since they go up in value as you travel north on the map. If you want to pinpoint an exact place on a map, such as your own house, you will need to use a six-figure grid reference, which you get by putting together the numbers of the easting and northing that cross in its bottom left-hand corner. Grid references are easy if you can remember that you always have to go along the corridor before you go up the stairs.
