This is all why I have no real strong desire to believe in a third brother. Mycroft could just be kickin' it around London, without the interest or the energy to be particularly bothered about any sort of an estate that belongs to him or his brother. I don't really understand why a third brother is so common when it seems to make a lot more sense to me to just say that Mycroft isn't living at home. Why would Holmes ever mention it if he never even brings up his parents? We only see Mycroft a handful of times, too, so why should he mention it?

The third brother is a bit out of the realm of possibility to me, but hey, if someone could say something that outweighs the possibility that Mycroft can't be arsed, then I'm all ears. XD