What many people either don�t understand or simply forget, is that electricity is a fuel which can only be produced in real time. All other fuels, gas, coal, petrol etc can all be manufactured and stored - we still have no means of storing mains electricity.
In order for us to enjoy a flicker free mains power supply, the generating companies have to constantly measure the load being drawn by consumers at any one time, and together with computer predictions for time of year, temperature etc, they are responsible for maintaining a generated power level just in excess of the real time demand load factor.
If as the other day, not one but two significant generating stations fail, then it becomes impossible to maintain the wattage supplied to the national grid and at the stipulated 240 volts. Hence automatic protection devices will trip and shut down areas of the country where supplies cannot be maintained.
We are all living on a knife edge these days, especially now where our ageing nuclear generating plants will soon be de-commissioned, and we will be reliant upon foreign nations allowing us to buy into their power sources, until such time as the UK government has the guts to say that we need to start building more reactors now.