On 19 January 1947 an agreement was signed between Westland Aircraft and Sikorsky to allow a British version of the S-51 to be manufactured under licence in the United Kingdom.

After delays caused by the need to modify and convert American-drawings to reflect British-sourced items and to replace the engine with a British-built Alvis Leonides 50, the prototype was first flown from Yeovil on 5 October 1948 piloted by Alan Bristow.

A total of seventy-two Dragonfly helicopters entered service with the Fleet Air Arm of the Royal Navy in the training, air-sea rescue and communications roles.

Dragonflies were used in relief operations in the North Sea flood of 1953 and a number were used by the Royal Air Force for casualty evacuation during the Malayan Emergency.

Examples were used by Pest Control Ltd for crop spraying and others were flown as executive transports by Silver City Airways, Evening Standard Newspapers and Fairey Aviation.