For years secret military bases were ‘hidden’ from Ordnance Survey maps for fear of espionage and national security. In a similar vein, the internal layout of HM Prison facilities were omitted on the commercially available maps, only showing the outline of the area. But, with the arrival of readily available aerial imagery and web mapping, it was decided to reverse that policy.
See the example below of HMP Dartmoor in the early 1990s.
Although prisons weren’t displayed on our maps in the past, our surveyors and cartographers still needed to capture the detail of the buildings, as they do today. We have 250 surveyors and they work in tandem with our Flying Unit to capture all the changes to buildings, road networks and the landscape across Great Britain.
Now that the map data is readily available, we have eight extracts of OS MasterMap below showing prisons across Great Britain. Can you name them? Post your answers on the blog and we’ll let you know the answers later.