Embattled British Prime Minister Theresa May. Credit:Bloomberg "This is a genuine crisis," he says. "A real and existential crisis, in historic terms. A complete redrawing of all international alliances and trading policies, as a nation." Leaving the EU is "stupid and illiterate", he says. There is a "cliff edge" coming, either at the Brexit moment of March 2019 or after a two-year transition period. When the country goes over that cliff edge into a "hard" Brexit outside Europe's single market and customs union, Lord Adonis says, there will likely be a serious economic crash. But the crisis is more than an economic one. Politics in Britain is being strained and deformed, as politicians try to process the demands of their "employers".

British Foreign Secretary Boris Johnson is tipped by some as a leadership contender. Credit:Bloomberg They're just not up to it, says Adam Boulton, a veteran Sky News presenter who has been reporting on politics since the Thatcher years. "I have never seen such poor calibre of leadership across the board at Westminster," he says. "Given Britain is in the process of taking a serious existential decision for a generation that is extremely distressing." Lord Adonis is a little more generous. "Referendums are all very well when people agree with their political leaders," he says. "But when they disagree – what happens? You have the extraordinary situation of a political class having to pursue a policy which almost nobody agrees with but [everyone] feels at the moment incapable of changing." At the end of October Lord Adonis, former Liberal Democrat leader Nick Clegg and Tory ex-chancellor Ken Clarke slunk into the European Commission to meet chief Brexit negotiators. Asked if they were there for advice on how to stop Brexit, Clegg replied "if only it were that easy", and Clarke joked "we are here to talk about cricket".

But Lord Adonis is clear. He's building a rebel alliance. He wants to stop Brexit before it's too late. "What I am playing for and increasingly large number of sensible people in Westminster are playing for, across all parties including the Conservative Party, is basically trying to stop this madness," he says. Corporate flight Brexit hasn't yet happened, but seismic tremors are already detectable. The British economy is now one of the poorest performers among its European contemporaries. A no-deal Brexit may lead to corporate flight from the City, the bedrock of London's corporate economy.

This week the Bank of America announced the move of 200 sales and trading staff to Paris and Frankfurt, a downpayment on its Brexit plan. Goldman CEO Lloyd Blankfein is flirting with Frankfurt and Paris on Twitter – praising the former city's weather and the latter's food. His Wall Street bank has leased new office space in Frankfurt, with room for 1000 staff. Boulton sat next to a bank director at lunch this week. "He said we're sending about a third of our workforce to Frankfurt." Carmaker executives warned a British parliamentary committee of the real potential for a "semi-catastrophic" halt to manufacturing following Brexit.

Meanwhile, Brexit negotiations are apparently deadlocked. The so-called divorce agreement, intended to cover a financial settlement, the rights of EU citizens in Britain and the status of the Northern Ireland border (to be the only land border between the EU and Britain, and one where the return of a border post could well mean a return to the Troubles), is still unsettled after six rounds of talks, and is almost inevitably going to stay unsettled well into the new year. Business want to know the outline of the vital trade and customs deal that will replace the union, but it's unlikely there will even have been discussion on its potential shape before March, just 12 months before Brexit. The government continues to insist you shouldn't judge a negotiation while it's under way – that such deals involve posturing followed by compromise, often at the 11th hour. "We have made a great deal of progress in the negotiations to date – far more than is understood by most people," Brexit secretary David Davis insisted on Thursday. 'The poison is running in the system'

Opinion polls show the British more or less stubbornly sticking to their 2016 vote, a narrow but uncontestable win for Brexit. But complaints from the London bubble of "experts" and "leaders" are getting louder. This Wednesday saw the launch of a new book, Brexit and British Politics, by two politics professors, Geoffrey Evans and Anand Menon. They say Brexit is reshaping the country's politics – "the poison is running in the system", they wrote, quoting (with approval) the Financial Times, which in turn channels the dismay of the corporate class. The book compares Brexiters with Leicester City fans who, "drunk on the success of winning the Premier League title felt, in the dark days of the following season, that relegation would be a price worth paying for that trophy". The launch, in Bloomsbury, was a very English affair. It revelled in gloom.

Menon says bitter Brexit divisions split the major parties. He recalls being in a room recently as Tory MPs "tore strips" off each other over agriculture policy. "A quarter of them said 'brilliant, Brexit means no tariffs, we can cut all agricultural support, we can become efficient, become New Zealand, we can have cheap food'. The other three-quarters looked at them and said, 'we come from rural constituencies, are you mad?'. "Both parties have these problems now. They are losing coherence and they were already losing the ability to lead their voters because there's no message." The referendum result provoked a "collective nervous breakdown" in the political class, says Heather Stewart, the Guardian's political editor. It led to the rise of Jeremy Corbyn and left a large chunk of Conservatives feeling "homeless". "MPs somehow don't hold judgments they've held for their political lives," she says. "Everyone feels a little bit at sea."

Boulton predicts an election within two years, with the "hidden subtext" of a choice between a hard Tory Brexit and a soft Labour one. It will be an odd election. "I've been sitting around the tables of rich people asking if they would consider voting for Jeremy Corbyn and they said 'yes' because they feel so strongly about this situation." Peter Foster, the Telegraph's Europe editor (his newspaper is reliably pro-Brexit), says he was told before the referendum by senior EU figures that "when you leave we're going to stick it to you". "The country has no conception really of what Brexit means … we're still in the phoney war," Foster says. "There's still a huge gap between what the EU is prepared to give us and the entire media and political conversation in this country – and those two things will collide at some point." Menon says the public wrongly equate a "no-deal Brexit" with the status quo. "They think 'no deal' is going to buy a car and you don't like the car so you come back with the car you have. They don't think it means they blow you up inside the old car." Meanwhile British Prime Minister Theresa May is toast, Boulton says. "I think the most likely scenario is that she will be gone and [ambitious Foreign Secretary] Boris Johnson will be the leader of the Conservative Party and the prime minister."

Stewart agrees the weak government and the prime minister are making Brexit harder. "[May] has a bunch of MPs asking 'how much loyalty do I owe you?'," she says. "They spend as much time thinking about how to manage the cross-currents in their own party and even their own Cabinet as they do the broad issues about the direction of the [Brexit] negotiations." Foster says Johnson "cut May's legs off" with deliberate interventions before her major Brexit speech in Florence and the party conference. The prime minister cannot even hold a Cabinet meeting about the Brexit settlement, he says. "The last round of Brexit meetings was a stocktaking exercise, a fig leaf, because nobody can make any substantive decisions … you're starting to hear in Europe a sense that the only way you can move this forward is if [May] goes. She's paralysed. The officials have a sense that she is completely broken ... they are frankly without leadership. Whitehall is conscious that there is a complete political vacuum." Lord Adonis is not sure how Brexit might be reversed. He needs 20 to 30 Conservative MPs deciding they need to stop it, or at least force another referendum and ask the people to put a stop to it. Faced with a cliff edge of economic decline, he says: "Parliamentarians who are by and large sensible and intelligent people will understand that we face a really serious situation as a country.