Development of the Westland Wasp / Scout family was the first general purpose light helicopter project that was completely British. Initiated by SARO in Nov 1957, the aim was to develop an improved airframe based on its earlier Skeeter helicopter, with a more modern design in general, but specifically for the powerplant. The result was the SARO P.531; two prototypes both powered by a 400shp Turbomeca Turmo 603 derated to 325 shp, had flown by Autumn 1958 from Eastleigh. Several Skeeter components were used in their construction, including the tailboom, short-legged undercarriage and rotor blades (the P.531 having a 4-blade assembly). In 1959, Westland acquired SARO (and Bristol Rotorcraft) and took development an important stage further by completing two more P.531/2 prototypes at Eastleigh with double the power and various other changes including a skid undercarriage. From these few airframes a successful and long-lived line of light helicopters was born.
The P.531 O/N version was also known by SARO as the H.AS/194D during its shipboard trials, which included suction-cup fittings to undercarriage legs from the flight deck of HMS Undaunted
between 1959 and 1961 as part of the Westland Wasp
HAS.1 development programme.