There are many ways to measure fairness in a society. Social mobility – the movement of groups or individuals in a social hierarchy – is one. The concept is as old as Dick Whittington, but has its intellectual origins in Pitirim Sorokin’s Social Mobility (1927), and came alive in Britain during the 1950s, first in books and plays and, eventually, in politics. In literature, the ‘working-class hero’ was defined by his upward mobility into the ranks of people he did not much like, and there the fun began. In Snakes and Ladders, Selina Todd says these partisans of the kitchen sink clung tenaciously to their working-class roots. In truth, it was their working-class roots that clung tenaciously to them. Nevertheless, in the new, more open Britain of the postwar era, there was plenty to suggest that there was room at the top, if not for everybody then at least for those who wanted it badly enough.

Given her previous work on women’s history and social class, which includes a book about Shelagh Delaney, you would suppose that Selina Todd and social mobility are a good match. But there you’d be wrong, because in spite of all her huffing and puffing, it’s impossible to know what she