Building on the success of de Havillands earlier twin engined Dove small passe aircraft, the companys attempt to produce a slightly larger airliner resulted in the first flight of the Heron in May 1950. Capable of comfortably carrying 17 passes, the Heron had a lo fuselage and wings than its predecessor and employed an additional pair of Gipsy Queen engines, providing reassurance for crew and passes alike. Early models of the aircraft were produced with a fixed undercarriage, but the Mk.II variant introduced a number of upgrades and improvements, most noticeably being the adoption of a retractable undercarriage, with the resultant reduction in drag providing a welcome performance boost. Although only 150 were built, Herons served with both the RAF and Royal Navy.