I happened to be in the city today, so I thought I'd have a poke around Richmond Buildings myself. As has been said before, there isn't that much to see on the south side, sadly. But I took a pic of the office block at 9-11 Richmond Buildings, which is where Nat's house would once have stood, as well as the office at No. 12, which I suspect survives from the original block (the brickwork looks pretty old to me, anyway.) So maybe that gives us an idea of what no. 9 also looked like, although I suspect it didn't look quite as spruced up back in Nat's day.
The numbering of the buildings doesn't really add up to me, no. 12 as it is today seems almost as wide as 9-11 combined, which doesn't tally at all with the 1790 map. It would make more sense if the office block was actually where 8-10 originally stood (rather than 9-11), and what's currently numbered 12 is actually the old nos. 11-12 combined into a single address. But I'm just speculating.


