Like its sequel, "Adventures of a Plumber's Mate", "Adventures of a Private Eye" is a cut above the average Brit sex comedy from the same era. There's more going on than just the standard "hapless lad has a job that involves meeting lots of frisky housewives with violent husbands", although there's that, too, of course. There's also a sub-film noir plot our inexperienced hero tries to solve, a gothic horror setting in a manor house with a macabre butler, and a séance.
More comedic set-ups - and the movie has more than you can count - means more jokes, which also means more likelihood that the jokes might land. Unbelievably, this time, a few actually do, and I found myself chuckling on occasion.
For future reference, this is the sex comedy where the other Tom Baker, Jon Pertwee, plays a swinging private eye - though there's certainly nothing about him that would suggest being a babe magnet - who leaves his business in the hands of his young protégé, who ends up taking on one of his cases. He gets a new secretary, and expects a sexy, available "bird" like the one his boss had, but instead gets an odd, ageless woman with round spectacles.
There's also a scene where he ends up dressed as a woman - nothing too special about that - but then has to perform on stage with a burlesque dancer.
Both the actress who plays the dancer, and the one who plays the odd secretary, are superior to the material, especially the multi-talented dancer.
I say check it out.