Thanks for those suggestions, Mo, Leeneia and JennieG!!

I guess it's sadly something I'll never know for sure, as we have almost no relatives left from his side of the family :(
She was a West Aussie nurse and he a returned soldier and they were married in 1922, had my Mum in 1923, her sister in 1925, then he died in 1926 - no pictures of them together and no idea how/when they met - but it was a love match!


However, I rather like this 1929 performance by the Mound City Blue Blowers of "I Ain't Got Nobody" / "My Gal Sal" :

https://www.youtube.com/watch?v=PfLs-jREjpk