Thank you for your replies. I'm not sure where John Roberts came from or if he's the John Roberts on the Maitland. He and his wife were living in Geelong in the late 1850s and their first two children were born in Geelong. I've had a look at the probate records for John Roberts, definitely not him. My next plan is to see if I can have a look at Catherine's Ballarat Asylum records. There may be a clue as to when John did.