While thousands of Extinction Rebellion protesters were marching along Millbank in London on Friday, something remarkable was happening just around the corner. The business and energy department said that the operators of planned wind farms on Dogger Bank off the Yorkshire coast were prepared to build and operate them for a guaranteed minimum energy price that was 30 per cent less than it was two years ago and about a quarter of the level being demanded in the early days of this industry.

At this rate, those Brobdingnagian windmills far out on the horizon soon will need no subsidy at all. Scale, engineering progress, human ingenuity and growing investor familiarity with an emerging technology have worked their wonders in driving down unit costs. About 8