On 24th March 1935, the Avro 652A Anson prototype K4771 took off from Woodford for its maiden flight in the capable hands of Bill Thorn. It went on to complete trials at Martlesham Heath but the flights weren’t trouble-free; although the aeroplane had built-in stability, feedback identified the need for more tail-plane area and a reduced elevator area. Roy Chadwick began work on these modifications for introduction on the production line.
The Avro 652A Anson was actually an evolution of the Avro 652 airliner designed and built for Imperial Airways. Development began in 1934 when the Air Ministry requested tenders for a maritime reconnaissance aircraft. The prototype differed from the production aircraft in that it had three large windows in the fuselage as opposed to the continuous window of the Anson Mk I. K4771 was also fitted with two 290 hp Armstrong Siddeley Cheetah VI engines whereas the Mk I used 335 hp Cheetah IXs.
The Anson prototype went up against the DH.89M (a military version of the Dragon Rapide) in Service Trials at the Coast Defence Development Unit at Gosport. The competition was fierce but the Avro machine was selected for the RAF’s requirement, having proved to be superior in both range and endurance.