The Spanish Inquisition - S2-E2
Trivia: In the "Semaphore version of Wuthering Heights" sketch, much of the sempaphore is nearly correct. The first two subtitled lines are "Oh. Catherine" "Oh. Heathcliff" - what is actually signalled is "Oh Oh" "Oheath". The nurse signals "SS" and the sleeping man does signal "ZZ".
Trivia: A piece of animation in the episode, by Terry Gilliam, which depicted Jesus Christ crucified on a telegraph pole, attracted some controversy. So much, in fact, that it was cut for all repeats and no longer exists on the master tape.
Chosen answer: The song you talk of was originally a poem by William Blake called 'Jerusalem'. It speaks of the possibility of Jesus having visited England. The poem has four verses but you only ever hear the Monty Python boys sing the first one which goes, "And did those feet in ancient time/Walk upon England's mountains green/And was the holy Lamb of God/On England's pleasant pastures seen?" If there's any sort of in-joke connected to it's use, I'm not aware of it. It seemed to just be the standard song/hymn they used when a song was needed that wasn't sketch specific. Some of the sketches it appeared in were 'Salvation Fuzz/Church Police', 'Buying a Bed' and 'The Art Gallery Sketch'. Something that may be relevant, though, is that the only one who was present every time it was sung was Eric Idle. Perhaps he just liked it?