If you’ve listened to any radio phone-ins about the discovery of refugee boats in the Channel, you’ll know that the fear of Others is barely overplayed either.

We ultimately must trust our seniors, even when we know they are lying. We can’t help but breed, optimistically and selfishly. Lanchester reveals with slow, steady control the cruelties of his strange new world and then socks you with their philosophical implications. It’s an idea he’s prepared to indulge if it means he gets to sleep with fellow Defender Hifa, but this half-hearted romance plot is soon disrupted by an attack that blurs the line between insiders and Others. In the meantime, his only escape route is becoming a “Breeder”, exempted from national service to produce children.

Kavanagh secretly aspires to join the supposedly meritocratic “Elite” who are occasionally spotted flying overhead. When he visits his parents, they can’t look him in the eye, ashamed that the world “broke on their watch”. They are responsible for the Change but have never done time on the Wall, which is, as Kavanagh says, “the single most important and informative experience in the lives of my generation”. It comes as no surprise that the young are disgusted by “the olds”. Others are marauding in “big numbers, dangerous numbers” (more than 94) according to a politician (known as “the blond baby”) who visits the troops to deliver platitudinous pep talks. It’s hardly a cakewalk for young Defenders such as Kavanagh, whose conscription begins at a point of national crisis. He, somewhat implausibly, pulls himself up the food chain only to prove that the system is not as infallible as it appears. In rare cases, a highly skilled Other might even work their way up to be a Defender, as in the case of Kavanagh’s captain. If they can prove they have valuable expertise, they can serve as “Help”, a euphemism for state-coordinated slavery whereby any citizen can “borrow” useful refugees. The incomers who make it over the Wall are put back to sea or put to death. The narrator’s tone may be chatty, but the world he inhabits is savage. Now he recasts our country as a frigid fortress, where national service and a diet of “turnips, turnips, fucking turnips” are endured with a needs-must stoicism. Lanchester has always made Britain, or the British abroad, his subject. “Always water, sky, wind, cold, and of course concrete, so it’s sometimes concrete-waterskywindcold, when they all hit you as one thing, as a single entity, combined, like a punch, concretewaterskywindcold.” He bestows some of this eloquence on his affable, bespectacled narrator, Kavanagh, a rookie Defender from the Midlands who manages to find countless amusing ways to describe his dark, unforgiving stretch of the Wall in north Devon. He is adept at breaking down complex concepts into accessible language peppered with handy little reminders – like a leather-jacketed professor taking a seminar in the pub. One of the things Lanchester is brilliant at, both in novels such as Capital (2012) and especially in his journalism and nonfiction, is simply explaining stuff. Lanchester reveals with slow, steady control the cruelties of his strange new world It’s a calculated extrapolation of our present anxieties about rising sea levels, anti-refugee populism, post-Brexit scarcity and intergenerational conflict, so day after tomorrow that it’s all but guaranteed to be invoked in newspaper columns and kitchen-table debates. This is the dystopia that John Lanchester has created in his fifth novel, an environmental fable that manages to be both disquieting and quite good fun at the same time. It is a whisper away from the sort of vision you can imagine Sajid Javid using to unveil a Tory leadership bid. Every British youngster is conscripted to spend two years of their life as a “Defender”, patrolling 10,000km of concrete walkways looking for “Others” who might appear at any moment from the sea. Britain’s coastline has been obliterated by a National Coastal Defence Structure, known to everyone who serves on it as the Wall. There isn’t a single beach left anywhere in the world. Ever since a climatic event known as the “Change”, life has, well, changed. T he scene is Britain, the time the not-too-distant future.

The world after the fall light novel