طيار اختبار
The High Lift was a "one-off" experimental, flying test-bed for the system of slotted flaps invented by R.T. Youngman. It was designed by L. E. Baynes AFRAeS, using components from the Percival Proctor, and built by Heston Aircraft Company Ltd. Test pilot Flight Lieutenant Ralph S Munday piloted the first flight at Heston Aerodrome on 5 February 1948, carrying the military serial VT789.