Many moons ago I used to work for the electricity board and the 'white meter' as it used to be called was set to switch on the E7 at 12.30AM and off at 7.30AM. When the clocks changed to BST the time of course altered to 1.30AM to 8.30AM. However a few years before I left they introduced the radio controlled meter and this switched on the meter @ approx 1.AM to 8AM throughout the year, regardless of GMT/BST. I am talking about the East Midlands area but generally most places in the country used the same system. If you look at your meter and see some flashing lights you know you have the new radio teleswitch meter. It used to be a signal broadcast on radio 4. Hope that helps, Rob
Both answers are correct. Under the Electricity Supply Regs, companies have to offer the tariff for a minimum number of hours each night. However it makes sense from the suppliers point of view to choose when they start the tariff, to balance supply and demand. They do this using a radio transmitter system, and have done so for many years. However many old systems with old White Meters will never have had the radio system fitted.