A long-running boycott of The Sun newspaper on Merseyside reduced Euroscepticism in the area and had a positive influence on its Remain vote in the Brexit referendum, university researchers have concluded.

Florian Foos of the London School of Economics and Daniel Bischof of Zurich university said their research showed that the mass media could influence public opinion, but that the effect takes place over years rather than a single political campaign.

Pro-EU politicians and campaigners have long claimed that newspapers such as the Eurosceptic Sun, owned by Rupert Murdoch’s News Group, have shaped the public’s view of the bloc.

Mr Foos and Mr Bischof tracked Merseyside’s view of the EU before and after the 1989 Hillsborough disaster, in which 96 Liverpool fans died during a game between the club and Nottingham Forest at Sheffield Wednesday’s stadium.

The Sun caused outrage on Merseyside by running a front-page story shortly after that wrongly blamed the tragedy on unruly behaviour by Liverpool fans, and this prompted many people in the area to stop buying the best-selling tabloid.

Estimated daily sales fell from 55,000 to 12,000, although The Sun has never confirmed the figures.

Kelvin MacKenzie, editor of The Sun in 1989, apologised in 2012 to the people of Liverpool after an independent inquiry found that the Hillsborough tragedy was not caused by fans at the game but rather failures by the authorities.

Mr Foos said that many of The Sun’s working-class readers on Merseyside switched to the Daily Mirror, which was positive about the EU.

“We show that attitudes towards the EU got significantly more positive in Merseyside during the boycott [of The Sun],” said the report by Mr Foos and Mr Bischof.

“Merseyside is about 10 percentage points less Eurosceptic in the 2016 EU referendum than the remaining UK compared to the 1975 [EU membership] referendum.”

The academics drew on data from the British Social Attitudes survey — an annual review of Britons’ attitudes to multiple topics including the EU — spanning the years from 1985 to 2004, after which it stopped recording where people lived.

The survey showed that the entire UK became more Europhile in the 1990s but that Merseyside did to a greater extent, and the academics compared the area with 21 other English counties with similar demographics.

“People in Merseyside were more Eurosceptic before Hillsborough than others in the north [of England] and that trend has been interrupted by the boycott [of the Sun],” said Mr Foos.

Recommended Lessons from the Hillsborough disaster

In 1989, 34 per cent of people in Merseyside wanted to leave the EU, against 25 per cent in comparable English counties. In 2004, the figures were 14 per cent and 18 per cent, respectively.

In the 2016 Brexit referendum, Merseyside voted 51 to 49 per cent to Remain, with 58 per cent of people in Liverpool backing staying in the EU.

Mr Foos said the vote on Merseyside would have been about 60 to 40 per cent in favour of Leave without the boycott of The Sun.

Mr Foos said he could not extrapolate the report’s findings about Merseyside across the country.

Had there been a boycott of The Sun in a southern English county, readers might have switched to the Eurosceptic Daily Mail rather than the Mirror, he added.

The academics adjusted their findings for factors such as party political support and demographic change, as well as the fact that Merseyside has received hundreds of millions of pounds of EU development funding.

Their report is being published at the American Political Science Association’s annual meeting in Washington on August 30. It has yet to be peer reviewed or published in a journal but is available on the internet.

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