Aircraft were sold to Australia, Canada, France, Tasmania, and a single example to New Zealand.
Two Percival EP.9s were delivered at the end of 1957 to Skyspread Pty Ltd in Australia.
The British Army purchased two in 1958 for evaluation, and they served for several years before being declared surplus and disposed of on the civil market.
The last aircraft was not completed by him and was finished by the Lancashire Aircraft Company who then went on to build four more aircraft. The rights for the EP.9 were acquired by Samlesbury Engineering Ltd in 1958, including assembled and partly assembled aircraft. The EP.9 was renamed the Lancashire Prospector EP.9 and three built with Lycoming engines.
The first of these was registered G-APWZ on 5-11-1959. It first flew on 23-02-1960 and attained its C of A on 22-04-60. Lancashire named the aircraft the Prospector and five aircraft were fitted with a 295 hp Lycoming GO-480-G1A6 and a three-bladed propeller before production ceased in 1960.