The Stephen Griffith Folk Song Index site that Texan99 put me onto in the comments of my recent "Apostasy Among Young Christian Leaders" post has been a lot of fun to graze around in and taught me a lot I had not known before. Plus some great things to listen to. I never knew this could be a round. Do people sing rounds anymore? I don't recall hearing them, even at the summer camp near where we stay. They're a good way to learn how to sing parts, and hear how notes can fit together.
If you want to hear the Scots-Irish origins in the tune, listen to the sustained lower foundational notes even in the mandolin introduction. Sounds like a bagpipe, doesn't it?