Why Boris Johnson could be a surprise triumph as PM

"Boris could get a deal through, then we have a mini-boom and he wins by a landslide". Interview by Tim Shipman.

Robert Harris ought to be happy, but he is not — and that's just as well because it means Britain's most accomplished thriller writer still has something to get off his chest.

When he greets me off the train from London it is hard for me as a fellow political journalist who writes books not to feel a pang of envy towards the man who wrote columns for The Sunday Times and The Observer before penning a dozen bestsellers. Harris, 62, is wearing a Martin Bell-style white linen jacket and not-quite-matching trousers, highlighting his tan of gently polished teak. Just up the canal towpath is his Victorian rectory. In the drive sits an Aston Martin and round the corner is a perfect country pub, sun dappling through the trees, where we find a table in the beer garden. There is a tremor of recognition from some of the other diners, but, in that very English way, no one stares as we both order crayfish cocktail and chicken and ham pie. I recall the instructions of my editor: "Just get him talking about politics. Ask him why he's not doing what you're doing any more." Well, probably the 25m book sales have something to do with it.

"To be honest, I find journalism a lot harder than writing novels, and doing a weekly column in particular," he says. "The build-up to it each week — I never lost a certain stage fright about it."

His new book, his 13th novel, is The Second Sleep (named because people in medieval times would sleep twice at night, with an hour of waking activity in between, and much of the book is nocturnal). It is at once quite unlike his others and just the same: a book fundamentally about politics. It is set, ostensibly, in the year 1468, a time of medieval barbarism, religious obscurantism and mud. The main character travels to a village that time has forgotten to investigate the death of the local priest, an amateur historian and archaeologist. It becomes clear that all is not what it seems. Some of the priest's artefacts are made of plastic (invented in 1907).

I have Harris's permission to reveal that it is an alternative history set eight centuries after the collapse of our current civilisation. "Every political system or social order passes away and I thought it would be interesting to write about antiquarians delving into a past that you believe at first is the Romans and then you realise gradually that it's us," he explains. "That was the start. This book is probably one of the books I've written where I am most preoccupied with things happening now and I put it into a fictional form. All my books are political in one sense or another. But I've not written a Brexit novel, I've not written a Trump novel. The characters around at the moment are too bizarre to equal in fiction, the situations are too improbable. Even if I finished it in July, by September it could be out of date."

Harris is very good on the way we view ourselves as the apogee of human development when, in fact, we are less able than many who went before, whose civilisations all collapsed in time. Harris, who wrote three novels about Roman politics, says, "The Roman Republic, Cicero, those people were just as clever. The things that their society produced — its oratory, its philosophy, its painting — were as sophisticated as anything we do. But still the system collapsed and the whole thing fell away, and I find that a very haunting idea. Mayan civilisation collapsed in about nine years and nobody knows why. The same could happen to us."

A recurrent image in The Second Sleep is of iPhone cases being exhumed from the mud, the bitten Apple symbol a metaphor for Adam and Eve's fall, the relics of a society where technology has made idiots of us all. "We've become utterly dependent on technology, and we are over-sophisticated and we've lost touch with what human beings used to be able to do," he says. "My father could strip down a car engine and put it back together again. He wasn't an engineer, he was a printer, but he could do that. And he would grow vegetables and paint the house. There are huge areas of the modern world that none of us know how they work, and if the plug was to be pulled, we would be quite incapable."

Harris reminds me that we have already had a taste of societal collapse. "That tanker driver's strike in 2000: supermarkets emptied almost overnight, and the queues for petrol, living in a rural area, made you realise what a thread things hang by. Then the financial crash, when there was serious talk about food distribution and ATMs failing. And it wouldn't take long, that's what frightens me."

You don't have to look far to detect his anxiety about the prospects of a no-deal Brexit, with the government preparing to cope with a shortage of food, fuel and medicines. Another of his "inspirations" was the current health secretary. "I was at a dinner and Matt Hancock was there and he said, 'Do you know the average home used to have eight days' supply of food in it and now it is only two.' For the first time in my adult life a government has been talking about these things happening. What did Churchill say? 'The only thing that ever frightened me in the war were the U-boats' — the supply chain. This country cannot be sustained without massive imports.

"A no-deal Brexit is just too risky. It may be all right, but I'm not sure I want the unexpected thing in the supply chain where insulin is no longer coming into the country."

Hancock's words reminded Harris of the old dictum that we are only ever six missed meals from revolution. Harris is not just warning about the future, he says he "spooked himself" enough to act. "I bought a wood-burning stove!" This seems like a very 21st-century middle-class answer to the problem of starvation.

It is not just the fragility of our version of civilisation that has him worried, but its impermanence. In the book, Harris notes that the buildings that survive are the old stone churches, while skyscrapers of steel and glass have collapsed into dust. "They are not built to last, are they? We have reached a peak of civilisation yet paradoxically we will leave nothing behind us except plastic dross: iPhone casings, plastic bags, nappies, cotton buds — that will be our memorial."

Harris believes that smartphones and social media have not just reduced us to a society of button pushers, but have damaged our mental wellbeing. "The modern connected world is driving everybody crazy. I think it threatens our mental health and the stability of our institutions."

He says his own four children have suffered anxiety as a result of social media. "Every family is touched by these problems. It's not an easy time to be a child. I've seen my children grow up with the paranoia of social media — their friends are all off doing something and they're not. I don't think that there is any coincidence that there are so many young people requiring mental health care or even medication."

Yet social media is not a temptation he avoids. "I would be sorry not to have Twitter, but sometimes when you have a successful tweet you feel ashamed because tweets that are successful are often glib or rude. Twitter is like the Roman forum, mobs go sweeping from one side to another, rumours start, Cinna the poet is killed rather than Cinna the politician. It's exhilarating but it's like getting involved in a huge pub brawl."

Harris also admits that technology that can connect us to every song or book ever written in seconds has left him "paralysed by choice".

But if social media and technology have left us infantilised and decadent like the Romans, he is clear that the real danger of collapse lies in the way it has encouraged the most "ambitious, able and amoral" of politicians. "Our institutions are like elderly buildings with some vast flood suddenly arising all around them," he says. "They simply can't cope.

"We have both devoted our lives to analysing and writing about power, and the impulse to power is a human constant. We've had a wonderful few decades of something approaching freedom and democracy, but I'm not sure if it is the natural state of the world. The main aim should be that the psychopaths don't get into power."

They aren't doing too badly at the moment, I remark. "There is no way that a figure like Trump could have become president except in this glib era," Harris says. "Boris is another symptom of it. He rose on Have I Got News for You — it really made him a household name."

Trump, he says, is "cleverer than people give him credit for", and his chaotic tweets are part of a coherent strategy. "Some of what he does is completely off the cuff and some of it is calculated, but the whole thing works towards a thought-out end. He's formidable."

Like everyone in politics, Harris has a good Boris Johnson story. "I sat with him once in this very pub, 20 years ago. He came and interviewed me. We had a very pleasant time. When the article appeared, he had manifestly made up a quote about me. He wrote, 'His friends all call him Moneybags' and this was in the headline of the piece. I said to him afterwards, 'Who are these friends?' He said, 'I made that up actually!' I've done a lot of interviews but I've never had a journalist cheerfully admit that they made something up."

He says Johnson's "plan" in government is to muddle through ("There is never a plan"). But he sees in Johnson something of the performer politician he saw in Tony Blair, to whom he has not spoken since The Ghost was published, his engrossing thriller that satirises the New Labour leader.

"The thing about Blair, what made him impressive, was that the public him was separate from the real him. The most successful politicians are the ones that distance this artificial public creation from their own person." Johnson's second biographer, Sonia Purnell, suggests that he created the character "Boris" to cope with family traumas. Johnson, who was christened Alexander Boris, is still known as "Al" to his relatives.

Harris says there is a long tradition of this personality politics. "Stalin had a great line. His son was always getting into trouble. He was a drunken air force commander forever throwing his weight around. He'd say, 'I'm the son of Stalin.' But Stalin lost his temper with him and said, 'I'm not Stalin, don't you understand? There's a creation that is Stalin, I'm not Stalin!'"

Yet, like many voters, Harris seems drawn to these characters. He speaks far more disparagingly of Theresa May, who, he says, suffered from her "lack of performance". "I've never met her, but I detected a vindictive streak in her, firing all those people when she came in. That has made me feel no sympathy for her implosion. There was a lack of largeness of character that is necessary if you are going to get to the very top."

Neither the Tories nor Labour appeals to Harris, who says he voted Liberal Democrat in the European elections — like many of his old New Labour friends. "We have reached the point where each party is as sinister as the other," he says. "I can't see myself ever voting Labour again, and I'm not naturally a Tory.

"To be honest with you, I think it's a tragedy. So much of what's gone wrong in this country has gone wrong because of Jeremy Corbyn's election. We probably wouldn't have had Brexit, which personally I don't think is a good idea, if we'd had a different Labour leader. The government has been able to get away with God knows what because they know that, in the end, the country would never elect Corbyn in a million years. He's a useful straw man. It's very depressing."

Harris is aware that some of this will sound like sour grapes from a chronicler and friend of politicians who failed in other ways. He admits his critique of society on the brink suffers from "a terrible tendency to bring one's tedious liberal prejudices to it".

"I don't want to fall into the old-man syndrome of everything was always better in the past, but it's hard to look back over my lifetime and not think that the politicians aren't as good. When I was 19, the Labour leadership contest to succeed Wilson was between Callaghan, Foot, Benn, Crosland and Jenkins. That was a formidable crowd. That generation got firsts, they were clever, they had been in the army, in the war, they went into politics and they were formidable. It is fascinating that people of that quality and drive and sense of history probably wouldn't go near it now."

With so many fears about the state of the world and the collapse of civilisation, you could forgive Harris for giving up and enjoying the views from the vicarage. But he still has ambitions: "I've always had a hankering to write a play, much more than I would like to write a film." Nonetheless, no fewer than six of his books are now heading for the screen.

An Officer and a Spy, his recreation of the Dreyfus Affair — which he likes best of all his books — is being shot in French for release in November. Conclave, his novel about the election of a new Pope, is scheduled to begin shooting in January by director Tomas Alfredson, who made the film version of Le Carré's Tinker, Tailor, Soldier, Spy. Andy Harries's company, which makes The Crown, is making The Fear Index, while Harris's Cicero trilogy is being adapted by Kudos, the creatives behind Broadchurch. The rights to Munich have been bought by Netflix. Finally, a TV series based on the fictional world Harris has created in The Second Sleep is already in development by Carnival Films, who made Downton Abbey. He'll be able to trade up for a new Aston Martin, if he wants one.

But Harris is one of those authors who are compelled to write. "I can't imagine not doing it, I started when I was about eight years old." He already has an idea for his next novel. "I like working hard between January and June, then having the summer off and then publicising the new book and then repeating that cycle."

His first book, Fatherland, paid for the vicarage and the other 12 have all been written there, looking down the sweeping lawn to the cottage where his wife, Gill Hornby, also a writer and sister of the novelist Nick, works, and the canal beyond. "I find that I can't work beyond lunchtime, so I like to be at my desk by eight and finish around 12, one o'clock. Seven half days a week is my perfect working pattern."

Whatever that book is, the master of the alternative history says he can't predict what will happen over the next year. What will become of the prime minister?

"I honestly can't answer. Because one brings to it one's own bias and a willingness, a constant desire for coherence. One of the pleasures of writing fiction, historical or political fiction, is you make the random chaos a coherent narrative. Reality does not obey these rules and Johnson, in particular, does not obey these rules."

Nevertheless he thinks the old rogue might make a success of it. "I can see that he will get through some version of Theresa May's deal — and only he could do it because in the end the ERG and the DUP will just have to go, 'Well, if that's the best he can do …' He gets that through and then a lot of people tell me there is a lot of pent-up investment waiting to go. We could, despite recent trends, have a mini boom and he could go to the country and win by a landslide because the Brexit party's goose would be cooked. Labour may still be saddled with Corbyn and a pro-referendum policy, which nobody is going to want, probably not even me! Boris is a lucky bugger."

Takes one to know one, I suppose.