This is a Notable Operational milestone.
This was the flight of the first of 9 Pre-Production protypes (PP1-PP9). PP1 was the development version of a Royal Navy ASW configuration aircraft. The type is now known by the designation AW101 post the merger of Westland Helicopters and Agusta into a single organization (AgustaWestland).
The flight took place at the Westland Helicopter's facility in Yeovil England and was flown by Chief Test Pilot Trevor Egginton and Deputy Chief test Pilot Colin Hague.
Source: Aviation Week and Space Technology/Oct 19 1987