(This is more than twice as many as 30 years ago. The number has been set by the National House Building Council's technical standards. They recommend 4 each in the kitchen and utility room, 4 in the living room, 8 in a living/family room with 2 near the TV aerial. Funnily enough they reckon there should be 6 in the main bedroom, and four in other bedrooms.
I have no idea why you would need so many sockets in the bedroom. The mind boggles.)
