The anecdote is well known, and many of us remember the song very well from the 1950s; but if you read the rest of this discussion (which started nearly 10 years ago and has been periodically revived over the years) instead of just the thread title, you'll see that there is strong evidence that McGuire based his 'new' song very closely -both tune and text- on an existing form or forms already circulating in oral tradition (though in America rather than Ireland). The specifically happy ending seems to be his most significant contribution to the 'new' piece, which is really just a minor re-write as opposed to an original song.