“All OS map are under Crown Copyright which expires after 50 years”. Which means I can take an OS from 1953 and use it to develop my own digital map. No restrictions whatsoever. Edinburgh has changed a fair bit in the last fifty years, but the city center has changed less than the outlying areas. This greatly reduces the amount of work required to produce a useful map. Thanks to Richard Fairhurst for the idea, and thanks to the National Library of Scotland for having a big collection of historical maps.
Who’d have thought it?