I knew, if I searched long enough, I'd find a castle in England continuously owned, and occupied, by the family who built it. There apparently being exactly one of them, it's no wonder the search took a bit of time. Still, they give tours of the place, and for ~ $200 the guy who owns it will take you 'round. I mean, what's not to love about a house that has to warn people "do not climb on the cannon"?

On reading their website, the whole bunch seem to be quite nice people. Might have to mark that as a stop if we ever manage to drag ourselves out there.