By Giles Darkes — HTT Cartographer Most of the maps that we produce use a digitised version of an OS map from somewhere between 1880 and 1930 as the base map, and we then add the historical information to it. The OS map is converted into a vector digitised form, and that means capturing the main features on the map and converting them into points, lines and areas.  Once they’ve been converted, it means that we can apply a cartographic style to them, and then add the historica