One thing I know that happens in Jane Austen period novels, which I don't know if it's still the case during the Holmes stories because the first of them is some 70 years after the last Jane Austen book, is that men will own property but not actually live in it. I *think* this was especially true for unmarried men, since they were supposed to be in the city meeting women. Of course, some men like the country and would go there more frequently, and some men hated the country and would stay away as much as possible. I know Darcy had a housekeeper and groundskeeper that ran the household while he was away.

This is only what I've gotten from her novels, so it could quite possibly be wrong. Just a thought into how maybe there could be someone taking care of the estate, but without there having to be a third brother.

I want to rewatch Pride and Prejudice now...