Tuesday's power cuts were due to an "antiquated energy system", according to environmentalists.
Robin Oakley, head of Greenpeace's climate and energy campaign, said: "Britain's antiquated centralised energy system relies on a few large power stations, such as our aging and increasingly unreliable nuclear power plants. When they fail the impact can be enormous. Sizewell B for example, the plant that failed on Tuesday, has the single greatest need for back-up on the national grid.