Adventures of a Private Eye (1977)
The Adventures of a Private Eye is a 1977 British sex comedy film starring Christopher Neil, Suzy Kendall, Harry H. Corbett and Liz Fraser. It was the second in the trilogy of 'Adventures' films after the 1976 film Adventures of a Taxi Driver. It was followed the next year by Adventures of a Plumber's Mate, the final film in the trilogy.
More at Wikipedia.