Can too much of a good thing be bad? Consider wind power. The generous subsidies paid by UK electricity users to fund a drive towards renewable energy have boosted the profits of wind farm owners. But they have not produced many more turbines. Now utilities are snapping up the farms to make fast returns. If wind power can compete without subsidies, it should no longer benefit from them. However, the problem is not the size of the handouts. Rather, it is the constraints imposed by a cumbersome planning system.

If Britain is to meet ambitious EU targets to supply 15 per cent of its total energy demand with renewables by 2020, it cannot ignore wind power. The UK's geography means it commands about 40 per cent of Europe's wind resource, making it an ideal site for turbines. If onshore wind is becoming commercially viable then that is welcome. That, after all, is the purpose of the "renewables obligation" on electricity firms.