 The specification required a range of 500 miles (800 km) and a bombload of 2,000 lb (900 kg), originally comprising a single World War I vintage 1,800 lb (820 kg) SN bomb, but then changed to four 500 lb (230 kg) bombs carried externally or eight 250 lb (114 kg) bombs internally.The Air Ministry gave Avro a contract for two prototypes, designated Aldershot I, on 2 December 1920, in competition with the de Havilland Derby.The first prototype flew at Hamble Aerodrome near Southampton in October 1921.