Mystery '30s or '40s banjo mandolin

[PaddyO]

Hi everyone, I was recently given a banjo mandolin by an uncle. He played it as a boy in Australia in the '40s. She's a little beaten up but plays beautifully, amazing action and feel. I don't know if it was new when he got it but either way it would have to be a 30s of 40s instrument. It has no brand markings anywhere (on the outside at least - I'm reluctant to start surgery for the sole purpose of satisfying my curiosity!) Two small metal f-holes on the side of the body, with canvas(?) underneath them (see picture) might be a good diagnostic. Pictures are attached - if anyone has any ideas on who might have made this I'd be delighted to hear your thoughts.
Cheers!

[MikeEdgerton]

It wasn't made in the US, looks more like the UK style of banjo mandolin.