To cite one recent study, a group of Harvard economists published a paper showing that children who have particularly good nursery school teachers can expect to earn, on average, $20 more per week by the time they’re 27. If the last government had invested all the money it wasted on its BSF programme on early-childhood interventions, it might have done something to reduce the attainment gap. As it is, the gap in achievement between rich and poor dramatically increased during Labour’s 13 years in office.