You may need to use grid references to get to the scene of a major incident yourself, or to be able to brief colleagues on where the police cordon entry point is located because of normal road access being closed off.
Ordnance Survey maps, scale 1:50 000 and 1:25 000 are used by the emergency services.
Grid references are always given as "eastings" first, then "northings". On the map read the numbers along the top or bottom of the map first and then along the side. This will give a reference to within 100 metres on the ground.
So, first quote EASTINGS.
Locate the first vertical grid line to the left of the point you want and read the large figures in blue along the top or bottom margin of the map or on the line itself (e.g. 04).
Then estimate the tenths from the grid line to the point you want. For example, half way across the grid square will be 5.
The grid reference for eastings will then be 045.
Then quote NORTHINGS.
Locate the first horizontal grid line below the point you want and read the large figures in blue at either the left or right margin of the map (e.g. 03).
Then estimate tenths from the grid line to the point you want (e.g. 8).
The grid reference for northings will be 038.
The grid reference for the location you have chosen will be 045038.
To give a unique number you should prefix the grid reference with the two-letter code found at the bottom of the map in blue.
