Radicalism in America may be in retreat, but populism is never quite out of style. There is always some percentage in a celebration of the working stiff, the honest guy, the salt of the earth. At the moment, there is a raft of books about the qualities of the ‘grunt’ – the GI Joe who bore the heat and burden of the day in Vietnam. Every one of these books seems to have been made into a film.

Then again, the current crisis in American farming, with families being driven from the laid by mortgage foreclosure, has inspired many ersatz versions of The Grapes of Wrath. Documentaries about the Depression are recalled, with all the panoply of Hoovervilles and bonus marchers. And it may be an illusion, but