Hawker had been privately developing a vertical take off aircraft since the 1950s under the code of P.1127. The success of this private venture, and the subsequent service interest, led to an announcement in 1962 that a ‘tripartite evaluation squadron’ (TES) would be formed.
The Kestrel was a developed version of the P.1127 and nine of the type were ordered for use by the TES during its operations in 1965. The TES was based at RAF West Raynham and included pilots from the UK, USA and West Germany. Its role was to evaluate the vertical take off Kestrel in near service conditions.
As well as West Raynham the TES also used two nearby abandoned airfields as semi-prepared sites. Buckenham Tofts in the Stanford Training Area was used as an unprepared site and allowed the squadron to hide their aircraft in wooded areas.
The success of the Kestrel came little more than a year before its successor, the Harrier, made its first flight. Harriers would be in RAF service until 2011.