During the Second World War the UK organisation responsible for analysing much of the allies reconnaissance photography published a monthly information booklet on what it was doing, called Evidence in Camera. In March 1945 it published a final 'special edition devoted to the history and development of P.R. (Photo Reconnaissance) and P.I. (Photo Interpretation)' which GeoHistoric have reproduced.
Most of the printed copies have already been claimed but if you are interested a pdf version is available for free. The pdf is 7.53Mb in size, so if you use the Contact page to get in touch we will send you a copy.