happy birthday, Alan Bell!
I remember hearing this song as sung by Tommy Makem

http://www.releaselyrics.com/3c37/tommy-makem-%26-liam-clancy-windmills/ (with audio)

http://martindardis.com/windmills_lyrics_and_chords.html (with chords)

there are also sites offering mp3 of Makem-Clancy version of the song