"It's an expression of that thing; that as you get older, you look out the window at the world around you and don't recognise it any more. There's always been an element of that for everybody, everywhere. But maybe it's more intense now. People look at the world around them and there are more people who are not like them."
So says John Lanchester, 56, an award-winning author of five novels, including Capital and The Debt to Pleasure, and a diverse range of non-fiction – food criticism, memoirs and zingy books about economics. Lanchester is responding to questions raised by his superb new novel, The Wall.
The story, at once thrilling, philosophical and political, is narrated by Joseph Kavanaugh – Joseph K for short, in a nod to Franz Kafka. Joseph has been conscripted as a "Defender", one of thousands of young British people ordered to patrol a 10,000-mile wall that encircles their island. Inside the perimeter are terrified citizens; on the outside are the "Others", an unspecified enemy who do the terrifying. Or, at least, that is what Joseph has been told.
The Wall's title and premise inspire two lines of enquiry early on. What exactly is the wall defending the citizens from? And what are those inside its perimeter so frightened of? Talking at his publisher's offices in London, Lanchester responds with that opening statement: people nowadays being afraid of a world they no longer recognise.
Does he share those fears? "I absolutely don't," Lanchester says firmly.
"I accept that not everyone is emotionally wired that way. A lot of people have the exact opposite feeling about immigration. For me, it goes quite deep."
The entire planet, it seems, is uniting to help Lanchester promote The Wall. Immigration, globalisation, Brexit, Trump, a mounting refugee crisis, environmental collapse – you name it, it informs Lanchester's dystopian fable. Indeed, our conversation takes place as various crises reach boiling point. One obvious example is taking place close to Lanchester's London home: the British government's calamitous withdrawal from the European Union. Lanchester has looked on with disbelief. "It's been two and a half years! Nothing's happened. That is genuinely strange," he says.
Another ongoing political saga is United States President Donald Trump's willingness to hold America's federal government hostage over funding for his own, much-vaunted border barrier. "Because America is a country built by immigrants, Trump's wall does actually challenge the whole idea of what America is," says Lanchester, who, unsurprisingly, is not a fan.
"Trump said this tremendous thing about wheels and walls: 'They really are medieval,' he said. Which is hilariously wrong. He is literally 5,000 years out."
Nevertheless, Lanchester grudgingly accepts the effectiveness of Trump's medieval imagery. "[Trump] has that ability to think laterally and in tabloid terms," he says. "People understand the image of a wall. They get it, completely and fully."
These headline-grabbers may provide unavoidable contexts in which to read The Wall, but neither Trump nor Brexit were at the forefront of Lanchester's mind during its composition. If anything, he drew from his life and protean identity. "I present as fully British. I am British. But, actually, it's more complicated than you might think."
Born in Germany to Anglo-Irish parents, Lanchester was educated in England, but spent his formative years in Hong Kong. "It wasn't a thing that was talked about a lot, but it was there, that Hong Kong was built by refugees," he says.
One thing Hong Kong taught Lanchester was the fine line that separates safe harbours from dangerous areas, the places people are desperate enough to flee from and those that they aspire to live in. In this, the current vogue for building walls – at least on the Texan-Mexican border – is a simplistic response to a profoundly complex issue.
"Walls are very often about defining who you are," says Lanchester. "Almost all cultures have the same concept of barbarians. That is part of the way I imagined it in the book. The wall is there for practical reasons, but it is a very complete way of defining who the 'Others' are. All you need to know about them is that they are on the other side."
Joseph K's problem in The Wall is that he is neither the "Other", nor a citizen being "Defended". Lanchester describes his position on top of the wall as liminal – a threshold between one supposedly defined space and another. This could just as easily describe Lanchester himself. Both his life and work defy easy categorisation – never more so than in this novel. "I am very insistently asked to put it on a specific shelf," he says. "Is it an allegory? Is it a dystopia? Is it a metaphor? Is it a parable?"
Aptly, and perhaps inevitably, Lanchester sits on the fence about this uncertainty. In fact he seems unsure if there is even a fence at all. "Writing is a way of not being where you are, quite," he says. "Absence is very important in writing. It is one of the odd things about the modern appetite for readings and festivals and meeting writers in person. Writers, by definition, are people who prefer being absent. If you liked being there and commanding the terrain, you don't become a writer."
Lanchester says he is not disavowing his fiction, merely distinguishing the John Lanchester that loses himself in his novels from the "social being" who turns up for interviews. "It is slightly like being the straight man who is packed off to answer the questions," he says with a laugh.
How do both John Lanchesters view the future imagined by his book? "One thing that happens with books like this, set in a dark version of an imaginary future, is the intention to prevent that future from happening," he says.
The future that Lanchester sees most clearly concerns the spectre of irreversible climate change. "We can still avoid it," he says, citing the International Panel on Climate Change, which believes that global warming can be limited to 1.5°C
"We have already had one degree, but [this forecast] shows a dramatically different map of the world. Hundreds of millions of lives saved, or saved from a horrible impact. Just the difference between 1.5 degrees and two, which is the target of the Paris Agreement."
Given Trump's withdrawal from the process, is such action feasible? Lanchester says we have no choice. "This is a last moment. Collective action on a global scale. We can still halt it at that level. The seas would get warmer for centuries, which is a frightening thought in itself, but it would, in effect, be saving the world."
And who, at the end of the day, doesn’t want that?
The Wall by John Lanchester is out now, published by Faber