By the grace of God and through the machinations of Boris Johnson, tomorrow the Irish state coach will convey the Queen down the Mall to preside over the state opening of parliament. At around 11.30am, she will address the assembled peers and MPs: “My Lords and Members of the House of Commons, there now follows an election broadcast on behalf of the Conservative party.”

Well, probably not, but she might as well. It is always the case that the Queen is a jewel-encrusted ventriloquist’s dummy for the prime minister of the day. When Harold Wilson came to office in 1964, Private Eye put the monarch on its front cover with the speech bubble: “And I hope you realise I didn’t write this crap.”

This Queen’s speech is especially inviting of mockery. Mr Johnson, a prime minister more than 40 votes short of a Commons majority, has no capacity to pass any legislation that is the slightest bit contentious. The occasion will not offer any clarification about Brexit, because no one will know tomorrow whether the recently more optimistic noises about striking a deal will amount to anything. It is possible that this will be the first Queen’s speech to be voted down since 1924. That triggered an election, though it won’t necessarily be the case when so many Labour MPs are tremulous about facing the voters.

One thing I confidently expect to hear in the script put into the monarch’s mouth is that “my government” is going to be doing much more for public services. The Tories have suddenly started sounding like people who have discovered the joys of spending. Their recent party conference was bedecked with banners booming: “Invest in our NHS, schools and police.” Billions more are promised for “an infrastructure revolution”, splashing the cash on roads and broadband. A big pay rise is dangled before low earners as the reward for voting Tory.

The next election will be the first post-austerity election. I don’t mean by this that austerity is actually over for everyone; it isn’t. Nor am I trying to suggest that the extra spending promised by the Tories will repair all the damage done to public services. It won’t. The 20,000 new police officers they are pledging won’t replace all the numbers cut in the past 10 years. What I mean is that the political contest will no longer be framed in the language of austerity.

Facebook Twitter Pinterest Theresa May during a general election campaign visit to in Wolverhampton in 2017. Photograph: Steve Parsons/PA

The three elections of 2010, 2015 and 2017 all revolved around arguments about deficits, debts and fiscal rules. In the first two, the Tories prevailed with their case that Labour had spent beyond the country’s means and Britain had to tighten its belt. By 2017, when Theresa May called an early election in an ill-fated bid to improve her majority, a lot of the public had lost patience with austerity. Mrs May’s worst encounter with a television audience was when she was confronted by a nurse who complained that she had not seen a wage increase in eight years. The Tory leader floundered before provoking anger by responding: “There isn’t a magic money tree that we can shake that suddenly provides for everything that people want.”

Memories of that, and similar doorstep encounters with aggrieved voters, prompt the Tories to now claim that they have located a lush forest of magic money trees. They are promising the largest annual increase in public spending in 15 years and tax cuts on top. It is not hard to discern why. They are trying to cover the flanks that made Mrs May vulnerable to voter discontent in 2017. The Tories also know that they will need to replace the seats that they are likely to lose in Remain-supporting areas of the country. They hope to do this by taking Brexity constituencies in the north and Midlands represented by Labour MPs. To many of the voters that the Tories are after, state provision matters a lot and the protracted squeeze on public services has been especially painful.

Having examined the Tory promises, Paul Johnson, the director of the Institute for Fiscal Studies, warns: “The government is now adrift without any effective fiscal anchor.” The steely axemen of austerity now declare that they will spend like an inebriated sailor. In this, the Conservatives are part of a worldwide trend of parties of the right abandoning previous histories of presenting themselves as the people who do fiscal responsibility as they morph into populists. The Trumpification of the American Republicans is the most obvious example.

The shape-shifting of the Tory party on spending is a challenge for Labour. A hatred of austerity has been the signature tune of Jeremy Corbyn and yet austerity politics was the making of him in 2015 and it was the saving of him in 2017. One of the reasons he won the leadership in 2015 was the widespread feeling within the party that Labour had failed to mount a sufficiently robust counter to the austerity narrative of David Cameron and George Osborne. Ed Balls and Ed Miliband, who learned their politics as proteges of Gordon Brown, were always nervous of promising very much for fear of being painted as reckless. With Mr Corbyn, it has always been a case of in for a penny, in for a billion. He used austerity to his advantage again in 2017 by changing the nature of the battle. What Mrs May had intended to be a Brexit election turned into a contest in which a lot of the argument was about what her party had done to public services.

Facebook Twitter Pinterest The chancellor, Sajid Javid: ‘The steely axemen of austerity now declare that they will spend like an inebriated sailor.’ Photograph: Victoria Jones/PA

Since the Tories are always going to attack them as economically ruinous whatever they do, the Labour leader and his shadow chancellor, John McDonnell, have taken the view that they might as well go large, very large, with their spending promises. Mr Corbyn is rather unlikely to join those saying that the Tory pledges are cavalier and unfulfillable because Labour is committed to spending a whole lot more. Labour’s last manifesto came in at something like £75bn of extra spending a year. To the large number of pledges made then, including the expensive promise to scrap all university tuition fees, Labour has added a further massive heap. They came out of their recent conference pledged to deliver free personal care for the over-65s, more generous universal credit, an end to rough sleeping, free prescriptions for everyone, a state-owned bank and a state-owned pharma company to make cheap drugs for the NHS. When it comes to spending, there is no such thing as too much for Corbyn-led Labour.

The number and the scale of these additional pledges did not get as much coverage as they might have done because of all the other stuff swirling around Labour’s week in Brighton. One shadow cabinet member groaned to me that he had spent going on for £10bn while the party was at the seaside and barely got a headline out of it because his announcements were drowned out by the furore around the botched plot to depose Tom Watson and Brexit splits.

Both parties are running significant risks. Unless Britain’s economy unexpectedly starts to roar along, they are going to have a lot of trouble paying for all these promises without raising borrowing and/or hiking taxes by more than they are admitting. If Britain slides into a recession, they will find it even harder to deliver and a burst of extra spending could well be followed by another dose of austerity. And if Britain suffers a calamitously disorderly Brexit, no one’s promises will be worth the manifestos they are written on.

Then there are the electoral risks. Tory strategists are hoping that promising more for the public services will induce amnesia about the austerity years, or at least inoculate them against some of the anger. At the same time, it will make it somewhat harder for the Tories to attack Labour as fiscally incontinent when respected bodies such as the IFS are levelling a similar criticism at the Conservatives.

A lot of Labour’s spending promises are individually highly popular. If you pay for your prescriptions at the moment, getting them free sounds alluring. The historical problem for Labour is that wary voters have often concluded that the party’s promises are too good to be true and too lavish to be deliverable. Despite everything that has happened since 2010, Labour still trails a long way behind when pollsters ask voters to rate the parties on their economic competence.

Both will fight the coming election by promising an extravaganza of spending. Neither is being at all clear about who will pay for their pledges. I very much doubt that the Queen’s speech is going to leave us any the wiser about that.

• Andrew Rawnsley is Chief Political Commentator of the Observer