People gather last week in London in solidarity with MP Diane Abbott, who has been a target of racism throughout her political career in Britain and is currently suspended by her party for comments deemed to have been offensive. Photograph: Alishia Abodunde/Getty Images As well as being St Patrick’s Day, Sunday was the day before Labour’s Sadiq Khan was due to officially launch his campaign for an unprecedented third term as London’s directly elected mayor. He seemed determined not to step on a landmine as he stopped to chat in Trafalgar Square after helping to lead a parade of green...