An important moment during the so-called election “debates” last week occurred when a young lady in the studio audience told Theresa May that she had voted for Brexit because she had swallowed the lie that it would bring £350m a week for the health service. The prime minister, an uncomfortable Remainer and now an uncomfortable Brexiter, had no answer to this, resorting to the cliche that the government spends more every year on the NHS. This, like so many of the answers trotted out by her (also uncomfortable) team is an example of what Dr Johnson might have called “a last refuge of the political scoundrel”.

The crisis arises because the increase in NHS spending each year is nowhere near enough to meet the well-known demands on the service. As I understand it, extra NHS spending is running at no more than 1% a year in “real” – ie inflation-adjusted – terms, whereas merely to avoid going backwards the service needs an annual real-terms increase of 4%.

Furthermore, the situation threatens to get a whole lot worse, as the service suffers from the thinly disguised racism behind Ukip’s conquest of the Conservative party – and May’s obsession with reducing immigration almost guarantees an impending recruitment crisis.

Of course, the problems in the NHS are only the most publicised of the obstacles facing the public sector generally. There are also looming crises in the pensions business, as well as goodness knows how many problems facing this country’s schools and its transport infrastructure.

It all boils down to two essential factors: one, referred to in this column a few weeks ago, is the fantasy that we can enjoy Scandinavian levels of public service and welfare on US-style tax rates. (It is, by the way, scandalous that the right wing of the Conservative party and their ghastly tabloids have made “welfare” into a dirty word – while always promising tax cuts.) The major political parties are beginning to recognise this, up to a point.

The second factor is a decline to barely recognisable levels in the annual increase in economic productivity. As the economist Simon Wren-Lewis has pointed out, this goes back, like so many other economic and social problems, to the 2007-09 financial crisis. We thought we had learned a lot from the economic disasters of the interwar years, and for decades after 1945 policies conducive to growth were taken for granted.

This was all lost after the financial crisis – a crisis that itself illustrated how the lessons of the 1920s had been forgotten, most of which are readily available in JK Galbraith’s book The Great Crash 1929. George Osborne’s misconceived austerity programme hardly constituted the kind of policy for growth that would encourage business to invest in the pursuit of gains to productivity. Nor did his cuts to public sector investment. As Wren-Lewis reminds us, recoveries from past recessions have been characterised by periods of rapid growth. No such luck in this decade, and, having analysed the Conservative manifesto, the Institute for Fiscal Studies emphasises that what is in store if they get back with untrammelled authority is at least five more years of austerity.

This puts May’s claims about her “great national mission” in perspective. Brexit, we are told, gives us “an enormous opportunity”. Why, thanks to her lame acceptance of a narrow result in an advisory, non-binding and grossly ill-informed referendum, “we have the opportunity to change the country for the better”.

Well, who wants to change the country for the worse? Sounds like a rhetorical question, doesn’t it? But it isn’t. The people who in effect want to change the country for the worse, whether or not they realise it, are those leaders and would-be leaders – I fear this appears to include the Labour party too – who are embracing Brexit.

It was Boris Johnson who predicted, with his usual misuse of our language, that Brexit would be “a Titanic success” – a most unfortunate metaphor. Now, some of my fellow Remainers are hoping that when it becomes clear in due course that Brexit would almost certainly be a Titanic disaster, even our present generation of leaders may recognise the need to reconsider the entire project. The terrible truth is, however, that much damage will have been done meanwhile. Indeed, one reads and hears almost daily of decisions that are already being taken by firms dependent on the single market to relocate at least part of their operations, and of academic institutions and research organisations experiencing serious recruitment problems, especially of the skilled immigrants who counterbalance this country’s skills deficiencies.

It has not been unamusing to witness the narrowing of the opinion polls and signs of panic in the May ranks. For anyone who cares about prospective damage from Brexit, an ideal result on Thursday would be a hung parliament in which neither main party could form a government without embarking on a coalition with the Lib Dems and SNP – a condition of whose cooperation would be to think again on Brexit.

Brexit is the biggest disaster facing this country since the second world war. That war brought Winston Churchill to the fore as a leader who opposed the appeasers. Where is the leader who can stand up to the Brexiters? Alas, not May.