I heard a discussion in a pub after this song was sung, wish I could remember all the details. But far from being a Pygmalion-type story, Kavanagh was indeed a drunken, 'grumpy old git' who knew that she was too good for him, and that's why there was no future in the relationship. She did indeed go on to better things, married well...I'd love to hear more details.
Noreen