Designed and built as a private venture without government assistance, it was cancelled when Westland took over rival helicopter producers and their more advanced projects.

In June 1958, Westland obtained an extension to their licence agreement with Sikorsky to cover the five bladed main-rotor, gearbox, tail-rotor, transmission and control systems of the S-56.

Faced with continuing government indifference, Westland decided to press ahead with a private-venture design for a heavy-lift transport, built around the S-56 systems but powered by a pair of Napier Eland turboshafts.

In March 1956, Westland decided to build the first prototype as a flying test rig with a tubular steel space frame in place of the main fuselage; cockpit power-train and undercarriage attached to this.

[4] The two aircraft were broken up; the components supplied by Sikorsky were stripped out and shipped back to the US to avoid paying import duty and the airframes were sold as scrap.