The Westland Wessex was a British development of the Sikorsky S-58, with a turboshaft engine replacing the original piston-engine radial.

On 4 December 1952 Grumman Aircraft flew the prototype of what was, for many years, one of the most important anti-submarine aircraft in the western inventory.

The Westland Sea King was derived from the Sikorsky S-61 series of helicopters, which had been designed to meet the requirements of the US Navy for an anti-submarine search-and-strike helicopter.