DVD Talk Forum - Challenge: Very tough title enquiry

Saw a British TV movie on the tube a few years ago, and I remember it being quite absorbing. I think it was made in the mid-late '90s.

Unfortunately I only have some rather vague memories: A husband and wife live in a house on the coast. He evolves into a very controlling, jealous person and, as the movie progresses, she more-or-less becomes a captive. Her neighbors begin to worry about her. One day she tries to escape and her husband kills her. He dumps her body (in a car I think) into a very deep, murky, junk-filled pool next to their house. He thinks he has gotten away with it, but I think someone ends up draining the pool by turning a stiff wheel.

That's about all I remember, and no, it isn't Les Diaboliques or any of its remakes/knock-offs.