10/31/2011. Remarks by Ray Watkins: "The Wyvern was the last fixed-wing aircraft designed by Edward Petter to be produced by Westland. In 1944 Petter proposed the W.34, with a Rolls-Royce Eagle engine driving contra-rotating propellers, as a naval torpedo carrying aircraft.

Westland was invited on April 14, 1944 to design an aircraft based on the W.34, but using a propeller turbine engine, to meet a new specification (N.11/44) for a long-range day fighter being drafted. Initial development and testing was carried out with the Eagle, which was also Rolls-Royce's last big piston engine, while the competing propeller turbine engines were under development.

The two engines being considered were the Rolls-Royce Clyde and the Armstrong Siddeley Python. The six prototypes, given the name of Wyvern TF.Mk.1 were flown with the Eagle engine. The W.35 Wyvern TF.Mk.2 was flown with both the Python and the Clyde engines.

The photo shows the first prototype Wyvern TF.Mk.2 fitted with the Python engine driving an eight-bladed contra-prop. The Clyde engined Wyvern TF.Mk.2 was fitted with a six-bladed propeller system. All production Wyvern TF.Mk.4s (later redesignated S.Mk.4's), some of which served operationally with No. 803 Squadron during the Suez campaign in October 1956, were fitted with the Python engine."