Long before Hackney North first elected Diane Abbott as its MP, my mother was a teacher in one of its primary schools. As a small boy I sometimes went with her, on long journeys by bus and train and across the wooden bridge over Clapton Pond, chanting about the billy goats gruff. Trip trap, trip trap. Visiting her staffroom was almost a whistle-stop tour of the British empire, with teachers from Jamaica, Trinidad, Nigeria, Pakistan, Cyprus and Ireland. All, I think, first-generation immigrants to the UK and all women – and all aware that those two things meant they wouldn’t...