Beneath all the noise of Brexit, an unexpected question is being quietly asked in British politics as an election nears. Is a Jeremy Corbyn government actually the safe option? If you’ve been persuaded by the years of warnings from most of the media and countless politicians that such a government would be extreme, chaotic, authoritarian and doomed to failure, you may find this question ridiculous. If you’re still a Corbynista, then the notion of him as a stabilising premier for today’s turbulent Britain may be equally absurd. For many believers, the whole point of Corbynism has been the possibility that it might lead to “the most radical government in British history”, as the leftwing theorist and activist Jeremy Gilbert yearningly put it in 2017.

Yet people in unexpected places are starting to consider a Corbyn government less risky than the alternatives. Earlier this month, Oliver Harvey, an analyst for Deutsche Bank in the City of London, told the Telegraph: “We see the magnitude of economic damage caused by a no-deal Brexit as much higher than [that caused by] policies proposed in the last Labour manifesto.” In the same article, Christian Schulz, an analyst for Citibank, noted approvingly that “Labour has become more decisively pro-EU”, while “a fiscally profligate no-deal Conservative government” had become less “enticing”.

Labour’s policies – so often dismissed as weird and naive – have in fact often carefully gone with the grain of public opinion

Off the record, other senior people in the City tell me they find the shadow chancellor, John McDonnell, who has been circulating among them busily in recent months, a serious and intriguing figure: a supposed Marxist who looks, and sometimes talks, a bit like a bank manager.

A similar thaw is under way in the more thoughtful parts of the business press. With western capitalism having a crisis of confidence, at the very least – this week the Financial Times announced “Capitalism: time for a reset” – Labour’s radical economic alternatives have begun to look more reasonable to some business journalists. The Economist, despite its longstanding support for the Thatcherite free-market reforms that McDonnell would like to reverse, has been covering the development of Labour’s new economic thinking with intense curiosity since 2017. This month, the more cautious, centrist FT has published a succession of long articles about “Labour’s new establishment” and its ambitions for Britain. While the pieces were still spiked with criticisms, the scale of the coverage has suggested a degree of respect – and that corporate Britain needs to understand Corbynism, and be prepared to make some accommodations with it.

Meanwhile, even some Conservatives have been daring to say the unsayable. In August, the Welsh MP Guto Bebb, a defence minister until last year, declared that “a short-term [caretaker] Jeremy Corbyn government” would be “less damaging” than a no-deal Brexit. A fortnight ago, the former chancellor Ken Clarke made the same heretical claim to the Observer, while conspicuously failing to add that a Corbyn administration should be a caretaker one.

Why are sections of the establishment being drawn to Corbyn and McDonnell now, having ignored or dismissed them for so long? On the face of it, the shift is all about stopping or moderating Brexit, at any cost. A little less obviously, it’s about the condition of the Conservative government: its snowballing incompetence, its increasingly manic and fantastical policies, its disregard for democracy and the law, its readiness to break up the UK, and its shallow pool of talent after almost a decade in power. (Priti Patel doesn’t seem likely to become one of the great home secretaries.) As Westminster participants and observers used to say, in more consensual times, it’s time for a swing of the pendulum.

Facebook Twitter Pinterest ‘The former Tory chancellor Ken Clarke made the heretical claim that a Corbyn government would be better than a no-deal Brexit.’ Photograph: Toby Melville/Reuters

Since Corbyn became Labour leader, he and McDonnell have worked hard to seem more respectable. During Corbyn’s decades on the backbenches he was a bit of a scruffy ranter; but in the Commons these days, with his neat white beard and stern glasses, he often acts more like a veteran school inspector, casting a disapproving eye over the government’s shoddy work. Both he and McDonnell now wear trim suits and ties to most public occasions; the contrast with Boris Johnson and Dominic Cummings’ careless dishevelment might make a good election poster.

This air of solidity is not a complete illusion. Since Corbyn took over Labour, the Tories and Liberal Democrats have each had three leaders. Meanwhile Labour’s policies – relentlessly dismissed as weird and naive by newspapers that saw no downsides to austerity and Brexit – have in fact often carefully gone with the grain of public opinion: renationalise the railways, raise taxes on the rich, put more police on the streets, avoid fighting foreign wars that lead to terrorism.

Potent governments, such as Tony Blair’s or Margaret Thatcher’s, usually have a good understanding of how most voters are thinking and living. Under Corbyn, Labour is at least trying to do the same, by beginning to confront the crises of capitalism and the climate breakdown, and how they affect people’s everyday lives.

In less than half a decade, despite never being in power, and only rarely leading in the polls, Corbyn’s Labour has helped crystallise what students of the great Italian leftwing thinker Antonio Gramsci would call a new political common sense: a widespread feeling that free-market capitalism has run its course, public spending needs to rise, and the way we manage society and the economy needs to change. As a keen Gramscian, McDonnell must be delighted.

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But Labour’s new respectability brings dangers. First, do British voters actually want a sober, reforming government? The polls currently suggest not: since Johnson began his cartoonish premiership, Labour has been consistently behind (though the margins have varied from substantial to tiny, usually according to the pollsters’ different methods).

Britain has arguably not had a Labour government with ambitions to profoundly alter the country since Harold Wilson’s first in the 1960s (and his reforming zeal didn’t last long). With Labour so often cautious since, many voters – and political journalists – have become unused to making the effort needed to consider novel and ambitious leftwing policies, such as McDonnell’s plan to change the balance of power in companies permanently by making their workforces into major shareholders. It’s easier just to dismiss such proposals as anti-business, and then get back to gossiping about the latest Tory leadership shambles.

Another problem for Labour with trying to play the grownups is that clearing up messes left by Conservative governments can be a thankless task. In 1974, Wilson’s second administration inherited an economic and industrial relations crisis from the disastrous 1970-74 premiership of Edward Heath. Wilson never quite managed to resolve the crisis, and soon his party was blamed for it – so much so that Britain’s struggles during the 1970s have been synonymous with Labour ever since.

Corbyn and McDonnell’s smart suits and new ideas will only get them a fair hearing from the establishment for so long. A Corbyn government, if it ever comes, will disrupt the status quo: “Change is coming,” McDonnell warned the FT this month. For the moment, some business figures may prefer a Corbyn government to a Tory one that can’t guarantee the food supply; but they may soon decide that an actual reforming Labour government is not such a good idea after all. As Oliver Harvey of Deutsche Bank reassured the Telegraph, “any market-unfriendly policies instigated during a Labour government” need only be “temporary”. They would apply only “until the government is voted out of office”. And just in case that doesn’t happen quickly enough, the papers read by Britain’s rich are full of articles about how to get your money out of the country.

• Andy Beckett is a feature writer for the Guardian