Hi, just spotted this chain which is something of a coincidence as I was in Usk yesterday trying to track down my maternal family links there.
The family name is Blakemore and, in the 1871 census, THEY were living at 4 Ash Street (James and Elizabeth with daughters Ellen, Elizabeth, Agnes and Louisa). In the 1861 census they were simply shown as at lower Ash Street and so I can't say if this was the same location or if they were living nearby.
I believe either then or later they had some connection to the Three Salmons.
There is a suggestion that the staff of the Three Salmons were housed in a 'large house perhaps in Ash Street'.
I see that 4 Ash Street has been redeveloped and there are a lot of properties on the land, so I assume that it was quite a large house.
Sorry that this get's you no closer, but it might provide some context and alternative options for research.
Good Luck