The Wedding Party (a.k.a. Sex) - S1-E3
Basil: Did you ever see that film, "How To Murder Your Wife"?
Major Gowen: How To Murder Your Wife"?
Basil: Yes, awfully good. I saw it six times.
The Wedding Party (a.k.a. Sex) - S1-E3
Basil: Hello, Fawlty Titties.
Answer: It's "Leisure Complex" by Dave Gold and Gordon Rees. Can be found on YouTube. The relevant clip is around 25 seconds in.