Ellan Vannin - written by Hugh Jones and recorded (live) by The Spinners around 1965.

It gets a frequent airing in various keys in our local folk club.
I do have an MP3 of the original recording if you're still looking for a copy of the song.

Am Am G Am
Am Am G Am
Am D G E
Am Am G Am
Chorus
A Am D Am
D Am Am G Am

A bit after the original request, but I've only just found the original post. Hope this helps.