The Boulton Paul Balliol and Sea Balliol are monoplane advanced trainer aircraft designed and produced by the British aircraft manufacturer Boulton Paul Aircraft. On 17 May 1948, it became the world's first single-engined turboprop aircraft to fly. The Balliol was operated primarily by both the Royal Air Force (RAF) and the Royal Navy Fleet Air Arm (FAA).
A Boulton Paul Balliol at the 1954 Farnborough Air Show
A preserved Boulton Paul Sea Balliol T.21 on display at the RAF Museum Cosford
Boulton & Paul Balliol T.2
The Armstrong Siddeley Mamba was a British turboprop engine produced by Armstrong Siddeley in the late 1940s and 1950s, producing around 1,500 effective horsepower (1,100 kW).
The Armstrong Siddeley Mamba-powered Douglas C-47B Dakota testbed in 1954 showing the slim outline of the Mambas
Mamba and propeller from the Apollo airliner