Who's a Good Boy Then? I Am! (1966)

Billy Oates meets a lady in a market and, taken by his kindness, she invites him to lodge with her and her husband. A rivalry soon develops between the young man and his landlord.

The uneasy relationship between elderly couple Thora Hird and Ron Moody and a cheerful stranger who moves in with them (Ronald Lacey). Written by Richard Harris (not the actor, but the future creator of Man in a Suitcase