Thanks, folks, for such quick replies. I'll now have to go back to UK records and try to find a link between Reuben and my known ancestors.
John, it's Alex Alber Probert, not Albert - I assumed it was an error initially, but he's on several electoral rolls. I found an Alex Probert who sailed Bremerhaven to Sydney 1911, but don't know if it's the same person.
Thanks, Kate