Ordnance Survey locations
Converting between OS grid references and longitudes-latitudes.
The Ordinance Survey is a UK-peculiar geospatial format, ubiquitous via street atlases, hiking charts and (yes) farming and epidemiological maps. It is explained in great detail is several places, but here's a quick overview:
The OS grid is a set of 25 squares, 500 kilometers a side, arranged 5-by-5 that …