Written (I think) by Leo O'Kelly of the group "Tir na Nog" and recorded on their debut album "Tir na Nog". I saw them at a pop festival at Weeley (near Clacton, England) in 1971 and bought both this and their next album as they came out.I think the words are on the album, so I'll look them out and type them in (unless I forget).
:-)
Ian