Jim Dixon has a good point about the internal rhymes, though the tune doesn't really pause to bring them out, nor were the lyrics written with capitalization indications to break the lines as such. Later versions also don't try to maintain the internal rhyming in new material, suggesting that it wasn't considered so very important to singers or listeners. Although the sheet music I transcribed is probably one step away from Geoghegan's original (meaning two steps away from his pen), it is the closest version yet produced to what Geoghegan himself wrote. Although internal rhyme argues that "lad" was probably there during his earliest draft, JBG may have omitted it himself, perhaps because he felt it improved the rhythm. Later versions seem mostly to not have it, either. So to say it is a "missing word" and "crucial" is rather a leap, as neither source evidence nor later evolution support that assessment.