Fawlty Towers is my favourite sitcom by some way, and the contribution Prunella Scales made is no small part of why it's so brilliant. She delivered one of my favourite lines (from Waldorf Salad).
Other Lady: “Uh, excuse me.”
Sybil: “Yes?”
Other Lady: “Do you think we could cancel our fruit salads?”
Sybil: “Well, it's a little tricky, chef's just opened the tin."
That's the 1970s for you!