What's this film called? Anyone know...?

I watched a film about 5-10 years ago and I'm pretty sure it was on
the BBC, pretty certain it wouldn't have been in the cinemas as it
felt like a BBC self production. Basically (I think) there are 2 men
who are business partners, and the wife (attractive blonde) of one of
the men discovers that her husbands business partner has a heart
problem, and should avoid certain things - one of which being sex. If
he dies then her husband gets the whole business.

Anyway she ropes him into having sex with her a few times, trying to
make him have a heart attack, but during this time he finds out that
he no longer has a heart condition so continues to have sex with the
lady anyway.

The male actor is vaguely famous, maybe late 40s/50s at the time, I
can picture his face but I have no idea of a name. At one point the
blonde lady dresses up as a tennis player, and later they have sex in
a corn field. This film has been bugging me for the last few days as
someone mentioned it to me, and I know what they mean but cannot find
out what it is!

HELP!
Maybe not a movie, but a drama? But wasn't a series. So annoying.
The business was quite possibly a pub.