The Scottish Aviation Twin Pioneer was a British STOL transport aircraft of the 1950s built by Scottish Aviation Limited at Prestwick Airport, Scotland. It was designed with both civil and military operators in mind. It was conceived as a twin-engined version of the Pioneer light transport.
Powered by two Alvis Leonides 531 radial engines, it was a high-wing cabin monoplane with a triple fin and rudder assembly and fixed tailwheel undercarriage. The prototype Twin Pioneer, registered G-ANTP, first flew at Prestwick Airport on 25 June 1955. Flight trials proved that the aircraft had a very short landing run and the aircraft was displayed at the 1955 SBAC Show.
Three pre-production aircraft were built for trials, and sales and demonstrations.In 1958 the 33rd aircraft was used as a prototype for the Series 2 with Pratt & Whitney Wasp R-1340 radial engines which had been ordered by Philippine Air Lines. A Series 3 aircraft was also developed to use the improved Alvis Leonides 531 radial engine.
(information from Wikipedia)