Performing an astonishing U-turn, Niall Ferguson, pictured, said the 'EU deserved Brexit' because of its failure on the euro and the economy, its aggressive foreign policy, open border migration and its failure to combat radical Islam

One of the country's most influential historians yesterday admitted he had been wrong to endorse the Remain campaign – and should have backed Brexit.

Before the referendum, Professor Niall Ferguson had been one of the most vociferous supporters of Britain staying in the European Union.

He had warned that leaving the EU would be 'the ultimate divorce', dubbing its supporters 'happy morons' and 'Anglo-loonies' who ignored the serious damage that would be done to the economy.

But yesterday, in an astonishing reversal, he said he had been wrong and admitted he – and the rest of the elite – had failed to listen to voters concerned about immigration. Brexit, he said, was the 'revolt' of provincial England.

The 52-year-old, who is a professor at Harvard in the US, also issued a scathing critique of the EU, which he said 'deserved Brexit' after failing on 'monetary union, foreign policy, migration policy, radical Islam policy'.

Speaking at the Milken Institute conference on the future of Europe in London, he said: 'I'm going to do something very unusual on these occasions, I'm going to admit that I was wrong.

'I characterise my 2016 in terms of post-Brexit traumatic stress disorder. I was arguing right up to the referendum for Remain but it's one of the few times in my life I've argued something without wholly believing in it.'

He said he had done so because he 'didn't want the Cameron-Osborne government to fall'.

With hindsight, he said, David Cameron should have rejected the 'absolutely risible' offer from the EU on migration and backed Brexit as well.

Professor Ferguson then listed the EU's failures over the past decade including the euro, which he said had been a 'disaster for all the reasons we said it would be in the 1990s'.

'It has been a disaster for southern Europe and has only worked for Germany and northern Europe,' he said.

'European security policy, especially with respect to North Africa and the Middle East, has been a disaster.

Before the referendum, Professor Niall Ferguson had been one of the most vociferous supporters of Britain staying in the European Union

'On the migration issue the European leadership got it disastrously wrong. On the question of radical Islam the European leadership has fundamentally got it wrong. One has to recognise that the European elite's performance over the last decade entirely justified the revolt of provincial England that was what we saw in Brexit.

'If those of us who were part of the elite spent more time in pubs in provincial England and provincial Wales we would have heard what I just said.

'This is not about GDP, it is principally about the complete loss of control of the EU's external border and what that implies for our country's future.

'I have had a kind of awakening. Brexit woke me up and reminded me I needed to pay much more attention to what the non-elite majority of voters were thinking.'

On Twitter he wrote: 'Cameron should have rejected [the EU's deal] and backed Brexit. Me too.'

Last night Brexit supporters welcomed his change of heart.

In a conference titled 'The Future of Europe,' he said he was wrong to defend David Cameron and George Osborne's arguments about the threat Brexit posed to economic growth. Pictured, the former Prime Minister and Chancellor on the referendum campaign trail together

In a series of tweets today, historian Niall Ferguson explained why he had changed his mind on Brexit and admitted he was wrong to back the Remain campaign

Matthew Elliott, who was chief executive of Vote Leave, said: 'It's great that people who supported Remain have woken up to the fact Britain is right to leave the EU. That is not just eminent historians like Niall Ferguson – large parts of the population who have found that Project Fear didn't come true now support Brexit.'

Less than a month before the June vote, Professor Ferguson signed a letter suggesting with Brexit we would 'cast ourselves adrift, condemning ourselves to irrelevance and Europe to division and weakness'.

He also wrote an article for the Sunday Times with the headline 'Brexit's happy morons don't give a damn about the costs of leaving'. In it he quoted warnings about the impact on the economy from the International Monetary Fund, as well as banks Goldman Sachs, JP Morgan and Deutsche.

'The risk of Brexit is already acting like a flashing red light to foreign investors,' he wrote. 'Project Fear? No. This is the consensus of the financial world, from the IMF down. Only a happy moron would ignore these dangers.'

Then, just two days before the vote, he described Brexit as 'the ultimate divorce' in an article for the Spectator.

A MAN OF COSMIC CERTAINTIES Professor Niall Ferguson relishes his reputation as one of the world's best-known, globe-trotting historians. He is, it must be said, not a modest man. On his own website he boasts he's 'an accomplished biographer' and that one of his books was 'published to international critical acclaim'. I suspect he was flattered when newspapers suggested that he earned $5 million a year — because he reacted by saying publicly that the figure was 'ridiculous'. Whether it was too low, he didn't say. Throughout the Brexit campaign, he posed as the intellectual heavyweight of Project Fear. With a tone of cosmic certainty and sophisticated historical authority — this is not a man who wears his cleverness lightly on his sleeve — he denounced the idea of EU withdrawal as 'horrendous' and a 'nightmare'. In the weeks before the June 23 vote, Ferguson, without a scintilla of doubt, predicted that the 'result would be a landslide for Remain'. A professor at Harvard and the author of 14 major books, the 52-year-old is renowned for his phenomenal literary output, assured media performances and gift for powerful language — using a knowledge of history as a tool to illuminate the present. In his best-selling books he has addressed history's sweeping themes — war, money and empire. Last year, he published a 1,000-page authorised biography of former U.S. secretary of state Henry Kissinger — the first of two volumes. In 2004, Time magazine named him as one of the 100 most influential people in the world, while he was also an adviser to the campaign of Republican presidential candidate John McCain in 2008. There can be little doubt that this conversion by a man with such impressive credentials is a major blow to the Remain camp. He is, as I say, not a man to whom modesty comes easily. Academic life in Britain is 'so shallow', he moaned when explaining his decision to base himself in the USA. Though thin-skinned over coverage of his own personal life, he has never been shy about dishing it out to those he derides. For example, he called Brexiteers 'Anglo-loonies' and made personal jibes about the great British economist John Maynard Keynes, saying he had no interest in Britain's long-term future because he was gay and childless. Ferguson later apologised, admitting his comments were 'as stupid as they were insensitive'. Considering his Brexit U-turn, how ironic it is that it was Keynes who, in defence of intellectual inconsistency, said: 'When the facts change, I change my mind . . .' Advertisement