Just for info. John Ball was a C14th "Hedge Priest" involved in the English "Peasants' Revolt" of 1381. There's a good summary of the background here with links to manuscript versions of John Ball's texts.The song is essentially taken from Ball's most famous text ("John Ball's Sermon Theme"):
"Whan Adam dalf, and Eve span, Who was thanne a gentilman?"
:-)
Ian