Minnesotan, I think your man would basically been a fishmonger dealing in fresh, dried & smoked sea fish, eggs, poultry, oysters etc' which presumably came up from Perth & that he also sold game in season, so not only would he have bought venison from this baroness he would also have provided her kippers.
The invention of the refrigerated ship on the Clyde by Bell & Co around that time meant that lamb & mutton could be imported in bulk from Australia & New Zealand, not only the wool as formerly. The arrival of this cheap meat lead to a collapse in demand for Scottish lamb & landowners cleared sheep & shepherds from wide areas, just as the people had been cleared themselves earlier in the century to make way for sheep & shepherds. Ironically much of this frozen meat was produced by the descendants of the folk cleared from the glens in the first place so some justice there.
This coincided with the boom in sporting estates with phoney castles springing up all over the shop, tweed-clad toffs pouring north every August & deer being encouraged in places where they were formerly absent, even being reared for release. We have too many deer in Scotland now & the bulk of what's shot is exported to Germany. My own g'g'g grandfather was fined £10 at Linlithgow for poaching, a lot of money then.
I'd rather have lamb chops myself.
Bests,
Skoosh.