The use of aerial images in archaeology has its origins in the 1920s. One of its pioneers was O G S Crawford, who was born in India, but spent much of his life in Hampshire and studied geography at Oxford.
During the First World War, Crawford had served as a photographer in the trenches, and as an observer in the Royal Flying Corps, forerunner of the RAF, where he took photographs as part of reconnaissance missions.
Crawford became interested in the application of aerial photography to archaeology. He produced two booklets of aerial photographs for the Ordnance Survey in 1924 and 1929. H G Wells named a survey aeroplane Crawford in his honour in his 1939 novel The Shape of Things to Come.
Crawford used RAF aerial photography to determine the length of the Avenue at Stonehenge, and in 1924, conducted an archaeological survey of much of Wessex, financed by the marmalade magnate Alexander Keiller.
He later entered into a public feud with Alfred Watkins after he refused to publish an advert for Watkins' book The Old Straight Track in his journal Antiquity, dismissing belief in ley lines as "crankery".
By the time of his death, he had acquired a near-legendary reputation among archaeologists, though somewhat tarnished by his becoming an apologist for Stalin's USSR.