I admit I originally thought it likely the housekeeper was Mrs Hudson... This is what I like about these discussions - I always seem to fall into the trap of assuming my interpretations are the obvious and only ones, and then I talk to other people here and suddenly see things from another point of view ^^

And much as I don't want to break up the old gang, I do sort of hope Mrs. Hudson got to do more in her old age than putting up with Sherlock Holmes ^_^