The Father Christmas Affair - S4-E7
Visible crew/equipment: When Mr Humprhries is talking about the whereabouts of Mr Grainger, explaining about the inability to remove the Al Jolson make up, you can see John Inman looking up before having his face shadowed by a boom mike.
Answer: That wasn't possible in 1972. Until recently squatting was a civil offence in the UK, not a criminal one, and removing squatters was a complex and time consuming business.