There is something ridiculous about Brexit Britain. It is a Carry On movie set in the past: we are living not at a historic moment but one laden with trivialised history. Boris Johnson tells us that with Brexit the nation will find its bojo as it found its mojo under Churchill. Brother JoJo tells us Brexit is the greatest failure of British statecraft since Suez; the greatest crisis since the Second World War.

Brexiters claim a deep continuity in British history betrayed by EU membership. Pro-EU people claim that the UK has never got over imperial delusions of grandeur. The reality is that both grotesquely over-egg continuity.

The problem is not just getting history wrong, but that history is invoked at all. The UK today could not dream of fighting the Second World War, or even invading Egypt. In 1940, Churchill led a great global force, second to none in the world. In 1956, Anthony Eden was at the head of the largest and richest economy in Europe with armed forces which more than matched this.

Today the UK is “just” another European power – a big Canada rather than a small United States, on a par with France and Germany, and on many measures behind them. Looking for past comparisons almost guarantees misunderstanding of this fundamental point, unless that is we look to Canadian history.

British history is one of radical discontinuity, and not quite what it is supposed to be. In 1900, the UK was a cosmopolitan place. It was full of immigrants, from Europe. Food came in from all over the world, free of tariffs too, much from Europe. British coal was vital to both Baltic and Mediterranean nations.

In turn, Britain depended on Swedish and north African iron ore; its eggs and its bacon came from Denmark and the Netherlands; Belfast linen depended on Baltic flax; the mines and railways on European timber. The newspapers and books were made of Scandinavian trees and North African grass.

The gravity model applied then as it does now. Even in 1950 the British economy was different from the continental European ones, not least in its weak agriculture. Even in war, Britain couldn’t feed itself. That historical reality was profoundly changed by British national policy, which transformed the nation after 1945. In many, many ways, continental Europe and the UK converged, on a continental model of national self-sufficiency. By the 1980s the UK was nearly self-sufficient in food, something nearly unthinkable in 1945 or 1914. After 1945 it also became a modern industrialised nation.

Facebook Twitter Pinterest ‘Weak agriculture’ is part of our heritage. Even in the war the UK couldn’t feed itself. Photograph: Bloomberg/Bloomberg via Getty Images

After 40 years in the EEC/EU, the economy has changed radically again. London is where world capitalism does business, no longer one where British capitalism did the world’s business, as before 1914. Foreign capitalists own the infrastructures and factories of the UK, rather than the other way around. The world owed the British rich a living – they now depend on the capital of foreigners. Politics have changed radically, too. The Conservatives were once the party aiming and failing to create a common market of the British empire. Yet in government at the head of the largest and most efficient economy in Europe, they turned decisively in 1961 into the party that applied for accession to the Common Market, having failed to get the EEC even then to budge an inch on its policies. Labour was the party of economic nationalism and of most anti-marketeers. Since then those positions have reversed.

There is no national British inventive effort, nor British national industry, nor even a national arms industry

Too many commentators have asserted that the Brexit vote represented an imperial throwback. A more plausible explanation is that it was an inchoate cry of nationalist rage from inner England, largely from those who grew up in a national age when there was national industry making national goods. There has also been far too much emphasis on the ideas of Brexiter politicians as imperialist or nationalist. Far more significant is a pining for Edwardian unilateral free trade. Rather than rebuild what is left of the British nation’s industry and agriculture, they would destroy it.

What Brexiters say about the British present deserves more attention. Where once there was a ludicrous declinism seriously underestimating British power, now a daft revivalism seems to be at the core of buccaneering Brexiter thinking.

They promise a global Britain, a global champion of free trade, a global innovation hub, a military power even in the South China Sea (but with low immigration). They pretend this already exists or is latent, as a leftover from before 1973, or as a product of the Thatcher revolution. This, too, is delusional, not least because there is no national British inventive effort, nor British national industry, nor even a national arms industry.

Brexit is not a portentous destiny that overhangs our politics. It is a mess of irreconcilable nostalgias. We shouldn’t grant to the Brexiters their own argument that they are somehow more in tune with the essence of Britishness as experienced through history, which we risk doing if we think they are helped by ghosts from the past. It is not a reflection on the realities of British life, of the present or of the past. It’s a very local phenomenon, which even if carried through, would barely register at European, much less global level. For the only power Brexiters have is to make us poorer, to inflict self-harm on the economy, and to damage further what little reputation British politicians have. Delusional as well as deluding, these banana-monarchy conmen and conduits for dark money want to trap us in a historicised never-never land.

But as reality bites, cloth will be cut to size, delusions dispatched, and the huffing and puffing will end. Brexit cannot in reality really happen. The explaining of realities will have to begin – that our productivity is low and stagnant, our health outcomes not the best, our people not the best educated or most enterprising, our entrepreneurs hardly the most important of the age. Any real politics of improvement will recognise we are not in the Premier League but in the lower divisions, and that football long ceased to be a game foreigners did not play.

• David Edgerton’s latest book is The Rise and Fall of the British Nation