The North-South divide in school performance is back on the agenda, with outgoing Ofsted chief inspector Sir Michael Wilshaw even suggesting it contributed to the vote for Brexit and calling for a minister for the North to remedy the situation. But as Richard Vaughan reports, for Knowsley in Merseyside – an authority that has spent more than a decade at the bottom of the secondary league tables – the supposed cures for low results have often made matters worse. He looks behind the headlines at a borough beset by poverty, which has become a case study in how local and national policy consistently fail to tackle underachievement