I would go for the divorce records - it looks like perhaps after he deserted Amy in 1905 he didn't return, and as part of the records they might mention when/where she'd last heard of him. Possibly she remarried in 1923 to William J C Bird which would explain the timing of the divorce. (Amy Elizabeth M Bird d. 1944 parents William James and Isabella).
I wonder if he got the idea for the "Hopetoun" name from the place in Victoria, or from the ill-fated first Governor-General of Australia, Earl Hopetoun, who would have been in the news for all the wrong reasons a couple of years before his marriage to Amy.