It's from David Ackles' second album, I believe. Ackles was a piano player, which may be why trying to accompany the song on guitar may be a challenge. I think that's why Carthy recorded it a capella. There were no notes on the Ackles recording, so I don't know if there's a true story behind it. Ackles himself became a college teacher after he recorded a couple more albums (on the Elektra and Columbia labels). He passed away a couple years ago I think.