Strictly speaking "the 4 Yorkshireman" sketch was not a python sketch. It was first performed on "At Last the 1948 Show" in 1967 two years before the first episode of Monty Python's Flying Circus was screened. It is credited to Tim Brooke-Taylor, John Cleese, Graham Chapman and Marty Feldman who all appeared in the original version. I'll get my anorak.