On the anniversary of Britain voting to leave the European Union, the Principal of Hertford College, Oxford, found some words to sum it up. ‘An entire society crucified by the delusional ambitions of Brexiteers chasing moonshine,’ wrote Will Hutton. ‘An anniversary to mourn.’ One might agree or disagree with his position on the European Union, but has British society really committed suicide? It’s a theme we have heard rather a lot recently: that Britain is a mess, an international laughing stock, leader-less and futureless. The case is normally made by Brits.

Rapid shocks — terrorism, the surprising election result, the Grenfell Tower disaster — have inspired forebodings just as the Brexit negotiations are beginning. This is not just the cry of shellshocked Tories or traumatised Remainers; it goes deeper. We’re seeing the revival of an old and familiar malady: ‘declinism’, a periodic fear that the nation has declined and is declining from some earlier time of strength, cohesion and success. Declinism is a syndrome: it assumes a combination of moral, political and economic failures. Britain suffered a bout of it in the 1880s when German competition in manufactured goods was first felt. It came back in the 1960s and 1970s, coloured by economic worries, rapid decolonisation and a perception of dwindling power and influence in every field.

Today, it has re-emerged as a core anti-Brexit sentiment. With a familiar mixture of despair (from the right) and glee (from the left), we are being told that we must eschew ‘nostalgia’ and ‘post-imperial delusions’, and ‘wake up to reality’ as ‘a small offshore island’, while the big strong powers of the European Union put us in our place, leaving us a stark choice between accepting the terms they dictate or facing economic and political disaster.

Some germ of declinism has been bred into all of us. Who would deny that Britain is no longer the great power it once was? Well, speaking as a historian, I would. Declinism is at best a distortion of reality, and mostly mere illusion. But so important is it in shaping our view of ourselves and our relations with the world that it demands sceptical scrutiny. It rests, above all, on two assumptions. First, that we have long been failing economically. Second, that we have suffered a loss of sheer power and hence influence in the world.

In the context of the Brexit debate, the conclusions are that the EU, ‘our largest market’, is our economic crutch; and that outside the EU club our feeble power and influence will dwindle to insignificance. We will be comparable, declinists scoff, to Albania or North Korea.

The belief in economic decline is a mixture of illusion and misunderstanding. Britain has been relatively wealthy at least since the Middle Ages, and industrial pioneers gave us a temporary dominance in manufacturing during the mid-19th century. This was a brief and unique episode. Naturally, other countries adopted British technology — helped by British capital and expertise — and began to catch up. This was desirable as well as natural, because it provided richer markets for British goods and services and valuable investment opportunities for British savers.

Since the 1880s, pessimists have always tended to compare British economic performance at any moment with those most rapidly catching up. When postwar European integration began in the 1950s, Italy, France and Germany were the most spectacular catchers--up, recovering from their wartime devastation and shifting their large and relatively unproductive agricultural sectors into industry.

This gave temporary ‘windfall growth’ that Britain could not equal, having no large agricultural sector to modernise. But an uncritical comparison of growth rates was mistaken for evidence of British economic failure. As early as 1953, an official report warned of ‘relegation of the UK to the second division’. This was the prime cause of our desperate pleas to join the Common Market in the 1960s and 1970s: Britain was ‘the sinking Titanic’, as one of Edward Heath’s advisors put it, and Europe the lifeboat.

Ironically, just as Britain joined in the early 1970s, European catching-up ended, and so did its seemingly superior economic prowess. In short, Britain’s long-term economic decline in relation to Europe never happened. Supporters of the EU nevertheless still maintain that membership rescued the British economy in the 1970s and remains vital to shoring it up today. In fact, British economic performance was never significantly affected by EU membership. Growth did not increase after joining the Common Market, essentially because trade was diverted from other markets to Europe just as Europe’s own postwar growth went into long-term deceleration. Despite the hopes and political efforts expended on creating the single market (not least by Margaret Thatcher), it has not proved very successful in increasing internal EU trade, and has never been fully extended into services, Britain’s main strength.

Due to both the greater dynamism of global markets and the problems of the EU itself, Britain’s trade with Europe has been declining sharply in importance for two decades. This was predicted to continue even if Britain had stayed in the EU. The recent overdue depreciation of an overvalued pound will provide some stimulus to our exports both inside and outside Europe, whatever the nature of the post-Brexit deal, and would more than compensate for possible tariffs.

Over the long term, membership (or not) of the EU has made no discernible difference to our economic performance. Britain’s increase in prosperity (growth in per capita GDP using purchasing power parity) has almost exactly kept pace with that of the United States ever since 1945, whether outside or inside ‘Europe’. The belief that leaving the EU must mean long-term economic decline therefore has no rational basis, just as the economic reports predicting that a vote for Brexit would mean immediate financial misery had no rational basis either.

The second element of declinism concerns the loss of sheer power and importance in the world. This seems as obvious to the stoutest Tory as to the most mocking Guardianista. After all, Churchill himself was haunted by it. Yet this too is largely, if not wholly, an illusion based on comparing a pessimistic view of our current state (whenever that might be — probably any time since the 1890s) with a highly inflated view of past power: usually the High Victorian age, or else round about the time of the battle of El Alamein.

The story of Britain being on a long slide to irrelevance always revolves round decolonisation. It’s quite true that the British empire is ‘one with Nineveh and Tyre’ — but so are all the other empires. No state has replaced Britain as the great global imperial power: empires are no longer possible or desirable, as Britain realised in the 1960s. Though a source of prestige (and of constant trouble — ‘a millstone round our necks,’ said Disraeli), it’s doubtful whether the empire was a source of wealth or power to Britain. Overall, it cost more than it brought in, especially after Britain turned to universal free trade in the 1840s, and colonies ceased to be an exclusive economic domain.

The empire’s power was used up in defending itself: it was, as one historian aptly puts it, ‘a brontosaurus with huge, vulnerable limbs which the central nervous system had little capacity to protect, direct or control.’ Throughout its imperial heyday, Britain had naval power, but on land was no match for Europe’s great powers or even its smaller ones. It was constantly worried by threats from France, Russia, Germany and even the USA to its economy, its empire and its home islands.

What of today? Britain is more secure from major external threat than for half a millennium. Taking a long view (say the last three centuries) it remains what it always has been — one of the half-dozen or so strongest states in the world, and one of the most global in its attachments, its vision, and its trade. Within this leading group of states, Britain has not declined but has actually advanced, being now more powerful than its ancient rivals France, Germany and Russia. The Cambridge international relations specialist Brendan Simms puts Britain even higher. Taking into account economic and military potential, population, ‘soft power’, diplomatic influence, political resilience and self-determination, he judges it the world’s third great power after the USA and China, and Europe’s only truly independent force.

Power is also based on intangibles such as self-confidence, a clear strategy and determination, and here we may be lacking. Russia, with an economy the same size as Spain’s, behaves like a superpower in the Middle East and is treated as one. But we fear we cannot even negotiate a mutually beneficial trade agreement with the EU. At least as much as by age and education, our attitudes seem to be determined by the division between confidence and self-doubt.

Declinism has always been a form of insularity, obsessed with Britain’s failings, but ignorant of those elsewhere. Today, unemployment is lower here than among most of our neighbours. Crime is falling. Schools are improving. We have evident problems too. But to see only weaknesses, and to diagnose them as part of a syndrome of decline, is to cling to a distorted view of the world and of our place within it. At worst, this undermines our position, and risks bringing about the very outcome it fears.

Brexit was a vote of confidence in our ability to shape our future as an independent democratic nation — a choice that few of our European neighbours feel they still have. We should not allow declinist panics to confuse the outcome.

The belief that ­leaving the EU must mean long-term economic decline has no rational basis

Spectator.co.uk/podcast Robert Tombs and Fraser Nelson on the return of declinism.