Well the whole purpose of "Cosher Bailey's Engine" and it's kin "There's a little pub in Wales" - is that it is (or maybe was) a popular English belief that the Welsh people used the saying "Did you ever saw" (spoken of course with a fake Welsh accent with a great deal of emphasis on the "saw". And the English were somewhat taking the piss out of the Welsh in the song. That's why it rhymes with 'before'.

Due to either political correctness, or plain ignorance, it has been reduced to "Did you ever see" in the DT.

bert.