One of the historic strengths of the Conservative Party has been its pragmatism and capacity to adapt. Depending on circumstance, the Tories have been Europhile and Europhobic, statist and laissez-faire, isolationist and interventionist.

In her party conference speech on 3 October, Theresa May suggested that another metamorphosis is at hand. “A decade after the financial crash, people need to know that the austerity it led to is over and that their hard work has paid off,” she declared. The Prime Minister’s mere use of the word “austerity” – traditionally derided by Tories as a leftist pejorative – was a mark of a transformed debate.

As recently as the 2015 general election, Labour, not just the Conservatives, subscribed to the view that further public spending cuts were unavoidable. The facts have changed, so May gives the appearance of having changed her mind. An anti-austerity Labour Party has wiped out the Conservatives’ parliamentary majority, and the current budget deficit – the economic metric used to justify cuts – has been eliminated.

“We got there in the end – a remarkable national effort,” tweeted George Osborne of the latter achievement. But the irony is that, at least according to Osborne’s definition, this is not “the end”. As chancellor, his ambition was to achieve an overall budget surplus, rather than merely one on current spending (which excludes capital investment). That target, based on current trends, will not be met until 2027-28. Based on past form, it will not be met at all.

The British right is now split between those who maintain that the UK has not endured “true austerity” and those who insist that “it hurt but it worked”. Neither argument bears scrutiny.

Total real-terms spending, it is true, has fallen by just 1.5 per cent: from a peak of £801.5bn in 2010-11 to £789.5bn in 2017-18. But this headline figure – inflated by the cost of a growing and ageing population and national debt interest payments – masks deep and unprecedented cuts.

Departmental budgets have been reduced by an average of more than 20 per cent since 2010 (and local government funding by 49 per cent) while more than £20bn of welfare cuts have been imposed (child benefit, for instance, is worth less than it was 17 years ago). Household debt stands at 139 per cent of disposable income and is forecast to reach 146 per cent (a phenomenon of so-called privatised Keynesianism: as the state borrows less, individuals borrow more to sustain their living standards). Rough sleeping, which fell by three-quarters under the last Labour government, has risen by 169 per cent since 2010. Nearly 1,000 Sure Start children’s centres and 478 libraries are estimated to have closed. Total public spending as a share of GDP has fallen from 44.9 per cent in 2009-10 to 38.4 per cent, well below the EU average and close to the US’s 36 per cent.

To justify this, austerians advanced three principal arguments: that high government borrowing represented a national emergency; that public spending cuts would stimulate private growth (“expansionary fiscal contraction”); and that excessive debt would “burden” future generations.

Though Britain’s budget deficit peaked at £153bn (9.9 per cent of GDP) in 2009-10, the degree of austerity imposed (and the emphasis on spending cuts over tax rises) was always a matter of choice, rather than necessity. For Britain – with its own currency, independent central bank and low borrowing costs – alternatives were available.

Rather than stimulating growth, austerity has depressed it. Even the IMF, a former cheerleader for cuts, concluded in 2016 that they did more harm than good. Partly owing to the slowest economic recovery in history, Britain’s national debt has increased from £1trn in 2009-10 to £1.8trn (or from 64.3 per cent of GDP to 84.3 per cent). Future generations will, after all, inherit a debt burden as well as an enfeebled public realm.

Far from the age of “big government” being over, voters now long for its return. The 2018 British Social Attitudes survey found that 60 per cent favour higher taxes and spending (the highest level in 15 years), 33 per cent support present levels and a mere 4 per cent wish to further roll back the state (libertarianism is, by some distance, the loneliest ideology in British politics).

To meaningfully end austerity, May will have to give the people what they want: tax rises. Her commitment to reduce the national debt as a share of GDP means that borrowing alone will not suffice. To end cuts in all areas, while delivering promised spending increases for health and defence, the government will need to find an additional £20bn by the end of this parliament – without a reliable Commons majority.

Meanwhile, from his numerous sinecures, Osborne can reflect on the political consequences of austerity. It contributed to the Brexit vote that ended his front-line career and that of his ally David Cameron. It has put the most left-wing Labour leadership for decades within reach of Downing Street. As Tory MPs freely profess, the Labour leader is setting the terms of debate, just as Osborne did from opposition in 2009. The austerians claim vindication, but if this is success, what would failure look like?