Theresa May’s “modern industrial strategy”, launched today, must avoid the ignominious fate of its predecessors. One by one they failed. Diagnosis of Britain’s problems is not difficult; treatment is harder. How can a government close the productivity gap, improve our low investment levels, heal the north-south divide, overcome our habitual pattern of inventing but not exploiting new ideas, and create an economy that “works for everyone”?

I do not presume to know all the answers, but I trust that the prime minister and Greg Clark, her business secretary, have begun by learning a lesson from the history of industrial strategies, Labour and Conservative: top-down solutions will not work; bottom-up ones might.

Subsidising solar panels has meant robbing the poor to feed the rich GETTY IMAGES

Clement Attlee’s government of 1945 nationalised the commanding heights of the economy. The result