Hey, hey, Homeward Bound is a completely different song to the one we're discussing here. Just because it contains the phrase doesn't make it a cousin. You might as well lump together everything that starts "As I roved out" or "One morning in the month of May."

Brian, I had missed your reference to the Wanton Seed version in one of the other threads. That tune is indeed quite similar to that of Mrs Fish, though (significantly I think) it is ABBA rather that AABA, and has no chorus at all. Textually, again, it is a completely different song.