Among the biggest things the prime minister wants you to know about him is that he is a revolutionary. A radical. An insurgent. Yes, on paper Boris Johnson may be a Bullingdon, Telegraph, establishment insider but in the flesh, dear voter, he is as much an outsider as you. He shares your desire to shake up this country like a drying Polaroid, to demolish the corroded old political-economic order and erect instead something shiny and new.

Such is the message repeated over and again by his team. And it works a treat. Accounting for last December’s electoral devastation, Jeremy Corbyn’s team pin part of the blame on how the Conservative leader outflanked their man as the rebel of SW1. As for pundits and politicians, they take seriously all the talk of a pinstriped insurrection. Even while broadsheet commentators this week deplore Priti Patel’s alleged bullying of senior Whitehall officials (denied by the home secretary), in the very next paragraph they chalk it up as the inevitable price of all that reforming zeal. To make an omelette, you must break a few eggheads.

It will be part of Labour’s job to point out that hiring 2,000 more police officers in no way makes up for the 21,000 that have gone

And so the Westminster class plays its old game, defined by George Orwell as giving “an appearance of solidity to pure wind”. For Westminster folk, mere winning is for racehorses: their champions must be invested with meaning too. Thus does the political elite justify itself to itself, and to the rest of us.

Early in 2017 people were so eager to believe Theresa May stood for something they spent months hunting an elusive beast they called “Mayism”. Today they wield their butterfly nets and go panting after Johnsonism.

Except pinning down the new prime minister may be the most impossible job in politics. This, after all, is the man who on the defining moment of his career, Brexit, wrote two newspaper columns: one for, one against. He vows to be “the most pro-business prime minister in history”, when previously he had exclaimed “fuck business”. While today he promises billions for the north and the Midlands, a few years ago he claimed: “A pound spent in Croydon is of far more value to the country than a pound spent in Strathclyde.”

Politics is what you say; policy is what you do. A politician as skilled as Johnson can keep up the rhetorical plate-spinning until he has to act. And on that his biggest test so far comes next week, with his government’s first budget – Johnson’s first big opportunity since the election to lay out his plans to transform the country and to back them with serious cash. The revolution that Johnson and Dominic Cummings promised us starts next Wednesday, when the new chancellor, Rishi Sunak, stands up in the Commons.

Or not. Since commentators are supposed to take the odd punt, let me lay here two bets. The first is that next week’s budget will be another publicity triumph for Johnson and co. The second is that it will completely fail to live up to the promises of transformative government that helped Johnson storm the last election and which are central to his premiership.

The reasoning for my first wager is simple: the government could simply re-announce what’s already lined up on economic policy and tell a very tidy story. Before he walked out of No 11, former chancellor Sajid Javid had already budgeted for about £100bn over the next five years to invest in the Midlands and the north. In last September’s mini-spending round, practically ignored in the melee of that autumn, he ensured that for the next year at least no government department would have to make any spending cuts. Add to that the legacy of Tories past: George Osborne’s four-year freeze on increases in benefits comes to an end next month. And there will be billions extra for the NHS, as Theresa May promised last year.

Put all that together, and you have more than enough for the next day’s papers, which will almost certainly trumpet the last rites of austerity and the start of a massive splurge. It will be part of Labour’s job on the day to point out that the 2,000 extra police officers budgeted for next year cannot begin to make up for the 21,000 that have gone over the past 10 years.

The Tory leader ran in the last election as a redistributionist, vowing that “everyone can get a fair share of future prosperity” and pledging in his manifesto to bulldoze “arbitrary tax advantages for the wealthy in society”. If he means it, then giveaways to the rich on entrepreneur’s relief and pension contributions should be scrapped next Wednesday and the savings spent on adult social care and the countless other cash-starved departments.

But any briefing to a friendly hack about taking away sweeties for the rich leads to huge pushback from Tory MPs. Higher costs on pension savings? A “moral disgrace … an economic farce”, harrumphed David Davis to Andrew Marr last month. Abolishing entrepreneurs’ relief? Backbenchers immediately took to WhatsApp to protest, “If we aren’t backing entrepreneurs, then who are we for?”

It is on such rocks that the Johnson regime’s uneasy alliance of true-blue Conservatives and Vote Leave’s “misfits and weirdos” will eventually founder. Meanwhile, by next Wednesday Sunak will have spent precisely 27 days at No 11. Formerly of Goldman Sachs, he is no ideologue but is instead what sociologist Aeron Davis calls a “reckless opportunist”: a politician who could have joined either main party or none, who is better at photo-ops than door-knocking and for whom politics is an entry on the CV rather than a vocation. Why would he begin his tenure as chancellor with a war over soaking the rich? Better to postpone any real head-scratchers for another day – say the next budget, this autumn.

Except that delaying big decisions is precisely not what Johnson was elected to do. And any Tory chancellor running a fiscal strategy based on low taxes, high spending and strict budgetary targets is setting themselves an impossible political task.

Amid all the talk of revolution that has hung over Westminster for the past few months, I have occasionally thought about a talk given by Thomas Friedman at the British Museum well over a decade ago. The New York Times columnist was talking about the promises of a green revolution, and he asked the packed house when was the last time there’d been a revolution in which no one got hurt. France in 1789 sent its aristocrats to the guillotine, the IT revolution put numerous firms out of business. Yet this one, Friedman claimed, would be painless, easy, even money-saving. “This isn’t a revolution,” he said. “It’s a party.”

The “painless revolution” – that is to say, no revolution at all – is surely Johnson’s preferred scenario. He is a people pleaser, an essay-crisis master, a spender not a taxer. He prefers the convivial, which is a perfectly fair personal choice, but a betrayal of what he offered as a politician.

• Aditya Chakrabortty is a Guardian columnist