Reid and Sigrist RS4 Desford VZ728/ G-AGOS was undergoing taxiing trials at Spanhoe airfield, Northamptonshire on 26 August, following restoration to fly with Windmill Aviation. The aircraft is registered to Leicestershire County Council, and was stored at the Snibston Discovery Museum at Coalville until it was permanently closed during July 2015.
Built in early 1945 at the Reid and Sigrist factory at Desford aerodrome, about seven miles from the centre of Leicester, the aircraft was designed as a small, twinengined conversion trainer, the RS3. It first flew on 9 July 1945 and was test-flown at the Aeroplane and Armament Experimental Establishment at Boscombe Down by Polish fighter/test pilot Janusz Żurakowski. The type was not adopted by the RAF, and remained with the manufacturer, registered G-AGOS. During 1949 it was modified for prone-pilot experimentation, with a lengthened, glazed nose, and fitted with a set of controls for a second pilot who lay on his stomach. Named the Bobsleigh and allotted the serial VZ728, it first flew in modified form in June 1951, and was used by the Institute of Aviation Medicine at the Royal Aircraft Establishment at Farnborough.
After the conclusion of test work in January 1956, the Desford had the second set of controls removed, which made it an excellent camera-ship, and in March 1958 it was acquired by Film Aviation Services. In 1963 it passed to Kemps Aerial Surveys at Eastleigh airport, Southampton. After disposal in 1972 the new owner painted G-AGOS in an inaccurate camouflage scheme, and it was flown at the Flight International/Aeroplane Monthly-sponsored Cranfield Air Pageant show in September 1973 by Nick Grace. The Desford was acquired by Sir William Roberts for his Strathallan Aircraft Collection in Perth, Scotland in 1975, but was disposed of in the famous Strathallan auction on 14 July 1981.