Bouquet of Barbed Wire (1976) (Episode 3)

Part 3 of 7 of the classic drama from 1976. With Gavin and Prue on holiday in France, Cassie takes the boys to go and visit her parents for the week, leaving Peter at home alone. During this time he gets to know his secretary Sarah better and before long they are having an affair. It's just unfortunate that he chooses his daughter's flat as the place to conduct their affair...