The play is well described on Wikipedia here. We saw the UK premier at the RNT.
What a cast; Henry Goodman, Margot Leicester, Ken Stott…David Thacker directed it. Theatricalia has this record for the play/production we saw – click here.

Janie and I rated it “very good indeed” at the time. I do recall it being a very interesting play and the RNT production was top notch, as RNT productions were wont to be at that time.
Here’s Michael Billington’s review:
Michael Coveney hated it:
Lots of Olivier Awards for the RNT production, including BBC Best Play Award.