Breezer's comparisons may not be a simple as it sounds, I was comparing my dads 2 bed bungalow, with my 3 bed detached, he had his thermostat set at 25c, on permanent, and mine 18c to 20c timed to come on early morning for 2 hrs, and evening for 5 hrs, very similar usage I thought.
The actual bill is in kw/hrs, at 2 tariffs.
MY meter is in Cubic METRES, his is in Cubic FEET.
they have a mathematical formula for converting to kw/hrs, and it turns out that the cubic feet meter works out more expensive per week, but looks less if you go by "UNITS".