The Royal Aeronautical Society had already celebrated its first fifty years when, in January 1917, the infant Testing Squadron of the Royal Flying Corps took up residence at Martlesham Heath in Suffolk, where it grew up to become the Aeroplane and Armament Experimental Establishment. It was at Martlesham that A & AEE built its reputation for thoroughness and accuracy in the assessment of aircraft and their equipment, a reputation which is still enjoyed today by the Establishment at Boscombe Down, its home since 1939. To see the origins of A & AEE, however, we must go back to the early months of the First World War, to the Central Flying School at Upavon on the northern edge of Salisbury Plain.