Well, it was cathartic at least. After three years of indecision and delay, Boris Johnson ripped through Westminster last week like, well, a potent laxative unblocking the body politic. Expelling what he'd no doubt call “the rancid remnants of remain” in the most ruthless cabinet clear out in history. Mind you, as anyone who has had cause to resort to such preparations, the relief is immediate, but it can be damned difficult to control the consequences.

Even the hapless Scottish Secretary, David Mundell, was evacuated. The Scottish Tory leader, Ruth Davidson, was reportedly “livid” at this because she had personally asked Johnson to keep Mr Mundell in post. But the new PM is clearly in no mood to indulge Ms Davidson. She had been part of an anti-Johnson conspiracy in the party, appropriately named “Operation Arse”. (Now out window, according to one wag). Whether she faces defenestration herself we will learn at Ms Davidson's first meeting with her new leader tomorrow.

He presumably wants to keep Davidson in Scotland. She delivered 13 valuable Tory seats at the last election, after all, and Johnson's majority is currently a shaky 2. But she is clearly going to have to bend the knee to the boss, and accept the new hard line Brexit doctrine of his government. The Prime Minister has made clear there is no room for doubters or “gloomsters” as the apostle of naïve optimism calls people who disagree with him.

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Johnson's new cabinet is a war cabinet. The campaign for the next general election has already begun, and social media is being weaponised as we speak.. Despite his protestations that he wants to deliver Brexit before “defeating Corbyn”, the general election is most likely to be before 31st October. This is because of the parliamentary arithmetic. He has no effective majority and is vulnerable to a no confidence vote at any time after 3rd September.

Johnsons first target in the war, his daylight bombing raid, was on the Labour left and liberal opinion in general, which has been universally hostile. For months we have been hearing that Boris Johnson is a “racist” and even a fascist. Social media worked itself into a lather about this hateful reincarnation of Oswald Mosley taking over the reins of government. “Was this what it was like in the 'thirties”, said one. Nicola Sturgeon herself has denounced Boris Johnson as a “racist”.

His response to all that was to install the most ethnically-diverse cabinet in British history. And that's not my assessment but that of the prominent BAME campaigner, Sunder Katwala of British Future. He tweeted last week that there: “is as much ethnic diversity around the Cabinet table as there has been in the rest of British political history put together". That was an extraordinary statement, which turns out to be true. The first BAME cabinet minister in British politics was Paul Boeteng in 2002. Petty shocking,that, when you think of it.

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Of course, for Guardian columnists, like Kehinde Andrews, this doesn't matter because Johnson-appointed ministers like Priti Patel and James Cleverly are the wrong kind of ethnic diversity. He dismissed them as “ministers with brown skin wearing Tory masks”. But it was always absurd to assume that politicians had to be left wing because of their ethnic origins.

It's the same with gender balance. Boris Johnson was careful to have more women around his cabinet table than in his predecessor's. He has installed prominent feminists like Nicky Morgan and Amber Rudd, the latter as Women's Minister. Again, they are the wrong kind of feminist for many the left. But this cabinet sends out a very strong message to the wider electorate, that claims that Johnson is a racist and misogynist are baseless.

This doesn't mean that Johnson is going to be a great Prime Minister or even a good one. It may be the most ethnically diverse cabinet, but it is also the most right wing government in recent memory. It is filled with ideologues like Dominic Raab, the Foreign Secretary, and out-and-out reactionaries like Jacob Rees Mogg, now Leader of the House. With Priti Patel, who used to support the death penalty, as Home Secretary, and the banker Sajid Javid as Chancellor, this is as right wing as any of Margaret Thatcher's teams.

This is a cabinet of Brexit ultras. Boris Johnson insisted on all of appointees committing themselves to a No deal Brexit, if necessary, by 31s October. They didn't quite sign the pledge in blood, but it was not far off. It will be most interesting to see whether Ruth Davidson signs the pledge tomorrow.

There's been much speculation about whether Boris Johnson, heart of hearts, really believes in No Deal. Isn't he just an opportunist saying what is necessary for his own personal advancement? When push comes to shove, surely he'll see reason. A crash out Brexit would wreck the economy, and where would the Tories be then?

Johnson probably believes that he is sincere, but is also capable, like his idol Winston Churchill, of abandoning any position if it becomes politically untenable. He presumably hopes that Brussels will come up with something to prevent a chaotic Brexit, which would damage many European countries almost as much as Britain. Germany is suffering a downturn at the moment, with business optimism plunging. Angela Merkell has proposed “over-writing” the Irish Backstop, whatever that means.

What it doesn't mean is replacing the Withdrawal Agreement, negotiated in good faith with the UK. Nor are the 27 prepared to throw Ireland under the Brexit bus. There is no form of deal that does not involve Northern Ireland remaining in a customs union with the Republic. Johnson must know that. This means Britain remaining in the EU Customs Union too, until a “technological solution” to the Irish border emerges. If it ever does.

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Logic suggests that Boris Johnson will have to fold. The idea of a negotiated No Deal is a contradiction in terms. There is no WTA free trade solution that does not also involve an Irish backstop. Indeed, the EU negotiators regarded the backstop as a great concession to the UK because it allowed friction free access to EU markets without the UK being in the single market.

So, as Churchill would put it, Johnson is a mystery wrapped in an enigma and topped with a blond thatch. He is style without any obvious substance. He is adept at trolling the left, and is not afraid to wield the hatchet in government, but has no great plan B. There are now many discontented former cabinet minister on the backbenches just waiting for him to fail - almost government in exile.

All that Johnson has is self belief. That like Alexander the Great, he can undo the Gordian Knot of Brexit by bold action. We won't have to wait very long to find out whether Johnson is a latter-day Alexander, or like Phaeton, son of Helios, is riding for a fall.