Imperial Airways Map of the Air Route
I have recently acquired a box of odds and ends from a long-deceased relative who used to work at Filton during the Concorde era. The most interesting item is an Imperial Airways Map of the Air Route between Egypt and Australia dated 1935-6 (price 2 shillings). It's about the size of an Ordnance Survey map and folds out like a concertina to over two metres long. It's double sided with maps showing the route and the many refuelling points along the way with the magnetic course and distance between each. There are also black and white photos of some of the en route landmarks.
Does anybody know if this is a particularly rare item? I've been checking Ebay for a while and haven't seen any there yet but there does seem to be quite an interest in Imperial Airways memorabilia.