Now you see it, now you don’t. Maps published by the Ordnance Survey from photographs taken by the RAF in the years after the Second World War were soon discovered to show on
some sheets sensitive areas such as airfields and military bases. After putting these maps on general sale in the late 40’s it was quickly realised that having such material in the public domain
wasn’t such a good idea, and after withdrawing existing sheets new versions were printed which obscured the military sites with painted-in fields or, in some cases, photographing the existing sheets with cotton wool suspended over areas to be hidden.
The maps were intended as an aid to town planning and reconstruction after the war and the examples shown here all date from 1947. For a long time copyright libraries such as the Bodleian and the British Library weren’t allowed to show the unedited maps to the public, a restriction only lifted in 1995.