Like others, I was intrigued by this claim, because I had never known those notoriously unreliable wind turbines to generate anything like such a high percentage. So, with the expert help of National Grid and the Renewable Energy Foundation (REF), I did some detective work. For a start, National Grid was able to tell me that there was indeed a brief moment on October 19 when wind supplied 25 per cent of our electricity. But this was at 5.30 in the morning, when demand is at its very lowest. The figure for the whole of that windy day was only 14 per cent. Furthermore, according to a detailed analysis by REF, what had really kept our lights on was that several other major coal- and gas-fired power stations stayed operating longer than planned, while wind farms in Scotland were actually having to be paid to go offline because their excessive output was causing problems for the grid in England.