The Saunders ST-27 was a Canadian twin turboprop conversion of the four engined De Havilland Heron with some engineering input from British Air Ferries ,and was on a sales tour

The second of 13 of these twin-PT6A turboprop conversions of the de Havilland Heron, developed with some input from ATEL at Southend. This airframe had an illustrious history as it was previously Queen's Flight Heron C.4 XM295 delivered in 4.58. Went on to fly with Air Atonabee but all ST-27s were withdrawn by the early Eighties. The ST-28 was an unsuccessful development which was to be built from scratch due to a shortage of suitable Heron airframes

This ST-27 demonstrator was the second ST-27 conversion. Starting out as De Havilland Heron XM295 for the Royal Air Force Queen's Flight. First flight a an ST-27 was March 27, 1970, the aircraft was broken up after retirement from Air Atonabee/City Express airlines in 1988.