The location of a postcode is defined as the average of the location of all the addresses in that postcode.
The location returned from this service is accurate to within 100 metres of this average location.
The location of a town, street or other free-format address elements is defined as the average of locations of all the postcodes in that area, weighted by the number of addresses that use that postcode. This may differ slightly from the locally-known "heart" of the area.
Locations are not available for certain postcodes, including:
- Some PO Boxes. Postcodes related to PO Boxes are generally considered to not have a physical location.
- Isle of Man, Guernsey and Jersey are not recognised by Ordnance Survey.
Longitude and Latitude
The locations provided by Ordnance Survey are produced according to the OSGB36 datum. GPS based systems and many other worldwide systems such as online mapping tools use the WGS-84 datum. You can choose which datum to use for the longitudes and latitudes returned by this service. By default, the WGS-84 datum is used.
As the original data is provided according to the OSGB36 datum, it is more accurate when using that datum. When converting the data to the WGS-84 datum, the accuracy can be reduced.