I can verify that the song was written by Andy M. Stewart [ whom I was at school with ]. He recorded it on the "Silly Wizard" album "Wild & Beautiful", which by a total coincidence, I was listening again to just a few days ago. The song lyrics and sheet music are on pages 32 / 33 of "The Andy M.Stewart Song Book"and Andy M. is listed as author/composer.
I have no knowledge of any cover versions, I'm afraid, so can't help with that.