Conversation so far:
What did John Cleese depart in regards to Monty Python's Flying Cricus?
John Cleese left the Flying Circus at the end of the third.
Why did Monty Python’s Flying Circus end?
Their humor was not always seen as appropriate for BBC, leading to censorship and the remaining Monty Pythons completed a final shortened fourth season before ending the show.

Question: what year did it close?
Self-contained rewrite: What year did Monty Python’s Flying Circus end?