A remarkable novel in a number of ways, it begins as one kind of story, about a rich, angry 15-year-old New York girl coming to live with her eccentric English relations in the country, and changes into another. Daisy is anorexic, furious with her father and his second wife, “Davina the Diabolical”, and her narrative voice, a mix of sassy vulnerability and cynical hopefulness reads like The Princess Diaries rewritten by Holden Caulfield. Aunt Penn’s remote rural idyll, complete with goats, dogs and four enchanting cousins, looks like the setting for a gentle transatlantic teen romance. It is not.

Within a week, a bomb goes off in London “and something like 7,000 or 70,000 people are killed”, Daisy says, casually. This is the authentic voice of adolescent indifference, but the five cousins, left on their own while Aunt Penn is abroad, try to behave responsibly. They drag provisions, blankets and books up to the lambing barn a mile away, and enjoy camping in the robust manner once celebrated by Enid Blyton and Eleanor Graham before William Golding and Ian McEwan reminded us what savage creatures children really are.

These children really are innocent, however, and their semi-playful act will eventually save their lives. Britain descends into war, as does the US. “No matter how much you put on a sad expression . . . we didn’t really care. Most of the people who got killed were either old like our parents so they’d had good lives already, or people who worked in banks and were pretty boring anyway,” our heroine observes. At first, the children treat it as a joke, for not only are they blissfully free from school but Daisy and Edmond are passionately, obsessively, in love. “It would be much easier to tell this story if it were all about a chaste and perfect love at an Extreme Time in History,” Daisy says, “but let’s face it that would be a load of crap.” There are no adults around to stop them having under-age sex, but the war and a smallpox epidemic means the girls are separated from the boys. Their harrowing journey back to the farm, and the cruelties they witness on the way, is what occupies the remaining half of the book.

Rosoff’s novel is not just about what happens when civilised restraints break down, but about how children whose childhood is brutally ripped from them may yet survive as damaged adults. Daisy is forced out of her selfishness by her protectiveness towards Edmond’s young sister, Piper, and the dog, Jet.

They survive against many odds, as do their cousins, but the ending breaks your heart. Animals, children, men and women all pay a price for something senseless that seemed remote but which becomes real and terrible, the price of being alive.

How I Live Now is outstanding — as a commentary on contemporary problems, as a superb story of love and war, and as a way of introducing those on the threshold of adulthood to the perils and passions of moral responsibility.

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