What sort of Britain will emerge from the Brexit earthquake? Will it still be united? What sort of role might it play in Europe and the wider world? Nobody knows the answers. But one can at least make plausible guesses. One conclusion seems clear: the UK the world thought it knew — stable, pragmatic and respected — is gone, probably forever. Lost reputations are not readily regained.

The most important transformation is in political leadership. Boris Johnson, a serial fantasist at best, is very likely to become prime minister. The leader of the opposition is Jeremy Corbyn, a man whose lifetime passion has been leftwing, anti-American politics. The country’s dominant force is Nigel Farage — a talented demagogue consumed by dislike of the EU. This is not a cast of leading characters for a country with a stable and mature democracy.

Then there is the risk of a no-deal Brexit. For no good reason, a parliament supposedly committed to leaving the EU thrice rejected the only deal Prime Minister Theresa May — a grown up, at least — was able to reach. In the case of Tory Eurosceptics, this was ostensibly over opposition to the Irish “backstop”. But they insist that this plan to prevent a hard border in Ireland is unnecessary.

In any case, it would only prevent the UK from making trade deals that are less important than maintaining good relations with the EU, probably unavailable (as with China and India), and even abusive (as with the US). The country is threatened with a no-deal exit — a plunge into the unknown that would exacerbate the already vicious blame game within British politics and between the UK and the EU.

The fiscal risks are also severe. Parliament may try to prevent an exit without a deal. One outcome might be a general election. If Mr Johnson made this into a vote on a no-deal Brexit and offered something juicy to Mr Farage, he might get almost all the Brexit vote, while the Remain vote is split. That could give him a landslide. He could then combine no deal with the irresponsible promises he has been making in his campaign for leadership. Philip Hammond, UK chancellor, suggests no deal would cost the exchequer £90bn a year. Mr Johnson’s tax cuts might cost another £20bn. To this must be added some ambitious spending plans.

There are also constitutional threats. Mr Johnson has threatened to prorogue parliament (end the parliamentary session) to stop it preventing a no-deal exit. This would amount to an executive coup against parliament. John Major, former prime minister, threatens to take such an action to judicial review. That would create a constitutional crisis — a result of injecting the foreign body of a referendum into a parliamentary system.

A bigger issue will be the future of the UK. Brexit is an English nationalist project. All the four nations of the union might then ultimately go their own way. Scotland is the most obvious potential defector. True, independence would be costlier to Scotland if England were outside the EU. But in such situations, people do not necessarily vote rationally — think of the English clamour for a no-deal Brexit. The Northern Irish might also decide that they would be better off to move inside Ireland and the EU, though the shock for both parts of the island would be considerable. Even Wales might ultimately find the embrace of “little England” stifling. Even without a break-up of the union, the tussle among the four nations over powers transferred from the EU is sure to be fierce.

I am assuming here that Brexit — quite probably a no-deal Brexit — is now inevitable. An additional reason for this is the horror many Europeans now feel. The fact that Mr Johnson described the French as “turds” in a recent BBC interview (subsequently excised) is characteristic. So is the way Brexit party members of the European Parliament turned their backs when Beethoven’s Ode to Joy was played. Why would Europeans tolerate such people if they have the choice?

The British have played an outsized role in the world. But what might be the future of England on its own, at open loggerheads with the EU? One option would be to follow behind President Donald Trump’s unilateralist and solipsistic US, probably as another enemy of the EU. The Corbyn option would presumably be to support any notionally leftwing tyrant he can find. Can a country dithering between Ayn Rand and Leon Trotsky truly count in the world? What justification can there be for its staying on as a permanent member of the UN Security Council?

What is happening is not worthy of a serious country. The conclusion is that the UK is no longer such a country.

martin.wolf@ft.com

Letters in response to this column:

Global apportionment of taxes is fraught with difficulties / From David E Spencer, New York, NY, US

The perfect cocktail to make Britain great again / From Philip T Foster, Albourne, W Sussex, UK

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