Theresa May will succeed in passing a Brexit deal through parliament because MPs are wrongly fearful that Britain could leave without agreeing a deal, Nick Clegg, the former deputy prime minister, has said.

Clegg, who last week became Facebook’s head of global affairs and communications, told the New Statesman: “All things being equal, it’s probably more than 50 per cent that she [May] might scrape home. But it’ll be like a bumblebee after a sting: she’ll die the moment she delivers that hotchpotch Brexit. If she has to rely on Labour support, and if she’s not already been axed by her party, she certainly will be after that.”

The interview was the last given by the former Liberal Democrat leader before his Facebook appointment was announced (he did not reveal his new position in advance). Clegg, a committed opponent of Brexit and a supporter of a new referendum, has since said that he will refrain from commenting on the subject.

But in his final remarks to the New Statesman, he warned that the fear of a no-deal Brexit was aiding May even though it “remains by far the least likely outcome”.

Clegg said: “The one thing that’s going really well for her [May] is the slightly lemming-like way that the whole political media community are going on and on and on about a no-deal Brexit when it remains by far the least likely outcome.”

He complained of “everyone dutifully blathering on about no deal, all these trade bodies paying consultants shit loads of money to calculate how much damage a no-deal Brexit would do, you’ve got this whole cottage industry of accountants and consultants and commentators.”

Clegg revealed that “one of the people intimately involved in the negotiations told me a couple of nights ago: ‘I wouldn’t put the chances at more than 3-5 per cent.’

“For obvious bloody reasons, negotiations never end on time in Brussels, time is the most fungible thing of all. The idea that you can have a collapse in the negotiations this month or November or December and that some of the most mature, sophisticated democracies in the world then sit around for three months twiddling their thumbs while the bond markets go nuts and you have lurid headlines about radioactive material not being transported and medicines not arriving...They might leave it till the last minute but of course they [the EU’s] could defer the Article 50 deadline or press the pause button.”

Clegg said that it remained possible that MPs would support a “People’s Vote” but that the spectre of no-deal made a Brexit agreement more likely. “I think there’s a shouting chance that we get such gridlock in parliament that people find the idea of another referendum more and more attractive, if for rather unheroic reasons. But I think I would still put money on that combination of factors seeing her [May] across the finishing line.”

The former MEP was as scornful as ever of pro-Leave politicians. “The Brexiteers are like people who are howling at the moon, or flat-earthers, who get more and more furious as the evidence piles up that the earth is oval-shaped, not flat.

“They don’t seem to understand that you can shout as much as you like, you can yell at Remoaners as much as you like, you can marshall the full force and fury of the right-wing press behind your cause but there are some very primitive forces of economics and politics which no amount of swinging at windmills will alter.

“It’s this constant, painful, grinding process where the gap between what they [the Brexiteers] believe is possible in their warped utopia and what is possible in a real world collide.”

Clegg said that May made a “huge and fateful error” at the start of her premiership by embracing “hard Brexit”, rather than pursuing a less divisive approach. “Instead of leaning against her Brexiteers by signalling that she was going to strike compromises to unite the country, she did precisely the reverse. From that moment on she was their creature and everything that’s happened since is just persistent thrashing around trying to eke out tiny, miniscule amounts of political space having been backed into a corner.

“Theresa May’s tragedy is that, in effect, what she’s done, if artfully at times through the good service of Olly Robbins [her chief Europe adviser] and others, is to try and either duck or obscure that clash between myth and reality rather than confronting it outright.”

Clegg, who regularly meets European leaders, suggested that they were increasingly open to reforming freedom of movement, regarded by some as the chief cause of the Brexit vote.

“They are now privately, openly talking about how, for their own purposes as much as to heal the breach with the British, they are willing to revisit the caveats, conditions and exemptions for freedom of movement, striking a new arrangement for an emergency brake.

“It’s just agonising because they all say privately ‘we weren’t that inventive ourselves back in the day: we weren’t under the same domestic pressure as we are now over the issue of the mass movement of people across borders in Europe and, secondly, we were being told by Cameron and his people that they were going to win [the 2016 referendum] anyway.

“But that now, if this what it would take to try and heal this terrible breach, we would jump at it. But then they say ‘listen, it’s very nice speaking to you Nick and we saw Tony Blair last week, John Major and David Miliband. But we’re not negotiating with them, we don’t have anyone to negotiate with in London.”

He said of French president Emmanuel Macron, the EU leader perhaps closest to Clegg, “Macron himself is, I find, the only politician of any weight left in Europe who understands the strategic significance of having Britain in rather than out. He is both the toughest negotiator now but also, potentially, the greatest ally to heal the breach.”

Clegg warned that MPs were wrong to believe that backing any Brexit deal achieved by May would settle the matter. “There’s no such thing as a quiet life by voting for her approach because this is only the throat-clearing phase - the real negotiations haven’t even started. If people are in despair at the negotiations now, they’re going to reach for a pistol in a few months’ time. The proper negotiations don’t begin until next year, these are just the preliminaries, the hors d’oeuvre.”

It was in the EU's interests, Clegg said, for a withdrawal deal to be agreed this year, reducing the UK's leverage in future negotiations on a new trade deal.

People keep forgetting how Article 50 is designed, it’s designed to defer all the difficult, concrete decisions to the point at which the departing member state is at its weakest. That’s the staggering stupidity of the Tories: they pulled the trigger of that mechanism without quite appreciating how much it put them at a disadvantage. There’s so much more leverage that Britain could have built up if only they’d been more patient.”

Nick Clegg was interviewed for tomorrow's New Statesman cover story on the Brexit crisis