Hi helendg
Sorry to learn of your EQ-related losses and every good wish for a speedy resolution regarding your home.

Mmm ... looking at the newspapers, electoral rolls etc. I'm not so sure that the William RICHMOND mentioned in the 1870 advertisements inserted by Walter, was in fact a lawyer.

The Otago Nominal Roll has
3 listings for 1870-71 for "a William RICHMOND at Adam Street" - under Dunedin City Electorate (x 2) and Dunedin and Suburbs Electorate (1).
All however give the same information -- showing this man had a "Household (voting) qualification" (meaning he was not a property owner) ... and none of the listings unfortunately give his occupation.
The NZ Electoral Rolls (@ Ancestry) have the same info and include him in 1875-76 also. Without knowing his occupation though, it's difficult to determine where he got to, after that date.
My thinking is, that if William RICHMOND was in legal practice, then, in an era when bankruptcies were rife and where numerous other transactions required legal representation, his name might have cropped up in newspapers ... or, he may have been found in electoral lists with his profession noted.
There was a RICHMOND who practised briefly as a barrister and solicitor in Dunedin - namely Christopher William (more usually known as William) - however that was around
1861, following a foray into politics.
This man went on to become Judge RICHMOND in 1862.
So it may be that the William RICHMOND of Adam Street, was simply just an acquaintance of Walter ? (Or someone known to both George and Walter ?)
~ Lu