Figures to be published are expected to paint a grim picture of the prospects for advancement for children from the poorest backgrounds dating back to the 1960s. Asked what was to blame for the lack of social mobility, Mr Willetts said: “The feminist revolution in its first round effects was probably the key factor. Feminism trumped egalitarianism. It is not that I am against feminism, it’s just that is probably the single biggest factor.”