Áine, I hope this helps. I sing the song in G minor, and the guitarist who accompanies me on this tune sent me a note saying this:
"I play mainly G minor, with F major and sometimes substituting an E flat major for the G minor."
He's well known for his casual approach *BG* He also acts as the rhythm section on this tune.
I would expect that substitution comes in the second part of the verse, when the melody goes higher. I'm a very beginning singer, and am just learning myself how all this works.
My hb. plays mandolin, I can ask him tonight what he's playing if this wasn't what you were looking for.
tori