From: "Spiny Norman" 

Easy. The Four Yorkshiremen. It is so famous if you just google
"yorkshiremen" you immediately get python references.

It isn't a Python sketch though. It comes from At last the 1948 show
(1968)and so pre-dates monty python. A crappy DVD has recently been
released with the original B&W version featuring Marty Feldman, Tim
Brooke-Taylor, Graham Chapman and John Cleese.

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