The 19-year-old star Millie Bobby Brown – known for Stranger Things , Enola Holmes and the Time 100 list of the world’s “most influential people” – has now written her debut novel. Nineteen Steps, set in the Second World War, is apparently based on her grandmother’s experience; it tells the story of a plucky teenage Londoner having romantic adventures as the Nazi bombs fall. Then comes a tragedy – oh no! And a choice between two suitors – oh no! Whatever will beautiful and brave Nellie Morris do? First, the title. From the outset of Brown’s novel, we’re primed for the climactic scene: Bethnal Green Tube station, where the Morris family shelters during air raids, has an unsafe staircase. Nellie warns us about it; the mayor of Bethnal Green mentions it; Nellie’s handsome love-interest cautions people he meets. Well, what is foreshadowing, I mused, but saying over and over what’s about to happen? This is very much Brown’s style.…