Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 133,120 pages of information and 210,773 images on early companies, their products and the people who designed and built them.
An experimental flying test-bed for the system of slotted flaps invented by R. T. Youngman was built by Leslie Everett Baynes. It used components from the Percival Proctor, and was built by Heston Aircraft Co.
1948 Test pilot Flight Lieutenant Ralph S. Munday piloted the first flight at Heston Aerodrome on 5 February 1948, carrying the military serial VT789, later registered G-AMBL.