To Catch A Butterfly (1977)

Kate had always adored Cornwall, and when the wealthy business tycoon Damian St. Ewan offered her a job there for two months - despite the fact that she didn't like tycoons in general and Damian St. Ewan in particular - she decided the opportunity was too good to miss. She had taken it for granted that the job in question was a secretarial one, so she was astounded when she arrived in Cornwall to learn that Damian had had something quite different in mind. It appeared that he wanted a temporary fiancee, to keep another woman at bay. And something told Kate that she would be playing with fire if she agreed . . .