The European Union target of generating 20 per cent of energy from renewable sources by 2020 is a legacy of Tony Blair, who in one of his last acts as prime minister agreed to the German-backed plan.

But the target immediately looked difficult to implement. The UK generates less than 5 per cent of electricity from renewable sources at present. When total energy consumption – including the fuel used for transport and heating – is taken into account, as the target demands, that figure falls to about 2 per cent.