Third of Brexit voters believe Muslim immigration is part of a secret plot to Islamicise Britain, study suggests

'Conspiracy theories are nowadays mainstream rather than marginal beliefs,' researcher says

Nearly a third of Brexit voters believe Muslim immigration is part of a plot to Islamicise Britain, according to a major new study that has revealed a pattern of deep mistrust for authorities.

The survey, by researchers at Cambridge University and YouGov, is the most comprehensive examination of conspiracy theories ever conducted and is the first time academics have looked into questions of trust in the media and conspiracy beliefs across countries.

Asked if they believed “Muslim immigration to this country is part of a bigger plan to make Muslims a majority of this country's population”, 31 per cent of leave voters said they did.

The far-right conspiracy theory, known as the “great replacement”, originated in France and often apportions blame to perceived elites, such as the European Union.

The figure among Remain voters was six per cent.

Almost half leave voters (47%) believed the government was deliberately “hiding the truth” about how many immigrants live in the country, compared to 14 per cent of Remain voters.

The study, however, painted a general picture of distrust among the population at large in the UK, with 60 per cent of Britons believing at least one conspiracy theory.

Disparities in the US among Donald Trump and Hillary Clinton supporters were even more stark, with 41 per cent of Trump voters believing in a "great replacement", compared to three per cent of Clinton backers.

The figures, which will be published in full on Friday, are the result of a six-year study spanning nine countries: UK, US, France, Poland, Italy, Germany, Portugal, Sweden, and Hungary. It was funded by the Leverhulme Trust.

Researchers defined a conspiracy theory as a belief that “some actors have conspired to do something covertly, usually something dysfunctional or evil”. They polled respondents about 10 common theories that had emerged from their research.

The figures also revealed:

• Brexiteers (12%) are six times more likely to believe climate change is a hoax than remainers (2%), though this pales in comparison to the almost half of Trump voters (47%). 
• A belief there are harmful effects from vaccines and that they are hidden from the public is more than twice as prevalent among leave voters (13%) than remainers (5%). 
• Fifteen per cent of Brexiteers and 11 per cent of EU supporters agree with the statement: “Regardless of who is officially in charge of governments and other organisations, there is a single group of people who secretly control events and rule the world together.”

Dr Hugo Leal, one of the project’s researchers, said anti-immigration conspiracy theories had been “gaining ground” since the refugee crisis first came to prominence in 2015.

“The conspiratorial perception that governments are deliberately hiding the truth about levels of migration appears to be backed by a considerable portion of the population across much of Europe and the United States,” he said.

Of Leave and Trump voters, Dr Leal said researchers “found the existence of a conspiratorial worldview linking both electorates”.

The team assessed levels of “conspiracy scepticism” by looking at those who refuted every conspiratorial view in the study.

Sweden had the highest levels of conspiracy scepticism, with almost half (48%) rejecting every conspiracy put to them, while Britain had a relatively strong 40 per cent rejection of conspiracies.

Trust in different professions was also investigated, with government and big business coming out worst across all countries in the study.

Around three-quarters of Britons said they did not trust government ministers or company chief executives. Distrust of journalists was equally as common.

“A telling takeaway of the study is that conspiracy theories are, nowadays, mainstream rather than marginal beliefs,” said Dr Leal.

“These findings provide important clues to understand the popularity of populist and nationalist parties contesting elections across much of the western world.”

A total of 2,171 people in Britain and 1,223 people in the US were surveyed for the study between 13 and 31 August. The survey was carried out online. For each country sample, figures have been weighted and are representative of the adult population.