@AC
>>"Firstly, some petty crook at HQ can deduce exactly when the house is empty - and send his mates round with a van."
Sure, since anyone and everyone working for the electricity company will have free and unmonitored access not only to raw meter data, but to related address details, etc.
And the employees will necessarily be less trustworthy then people currently working at ISPs or phone / mobile phone companies, postal workers, etc, who also potentially have information about when houses seem to be unoccupied.
>>"Secondly, some petty perv at HQ can guess when daughter comes home from school (10kW spike from the shower)."
Sorry to puncture your bubble, but if someone already knows that you have a school-age daughter, wouldn't they already be able to make a pretty good guess about when she'll be coming home from school, given even just the common knowledge that schools tend to finish about the same time?
And at least, unlike hundreds/thousands of people within walking distance of your house, someone in electricity HQ probably won't know whether your daughter is stunningly attractive and devoted to personal grooming, or a right minger who's so lardy it takes her ten minutes in the shower to get wet all over.
If you're seriously worried about someone miles away /potentially/ knowing less about your family than almost anyone in your neighbourhood who's even slightly interested in you, that does seem like an odd set of priorities.