SCOTLAND’S chances of being dragged out of the European Union against its will increased yesterday after Boris Johnson dramatically announced he would back the campaign to leave.

The Tory London Mayor is the biggest name yet to join the Out side and commentators believe he is the popular figure it need to connect with undecided voters south of the Border.

John Curtice, professor of politics at Strathclyde University, in Glasgow, told The National: “I don’t think Boris Johnson will have a great deal of influence north of the Border, but the fact that he is now campaigning for and may be leading the Leave campaign means that the campaign to remain in the EU will have a really serious battle on its hands.

“One of the things that was supposed to happen in the Prime Minister’s negotiations was that the Tory party came together to back the PM and that Tory voters would swing in behind Cameron – but this is not happening and things are going to be much more difficult.”

He added: “Boris Johnson is one of England’s most charismatic politicians. He is the best known Conservative politician next to David Cameron and he has a demonstrated ability to win over voters. He can reach across party divides. He is socially liberal but is also loved by the Tory blue rinse brigade.”

Johnson made the announcement outside his London home, minutes after texting the PM to tell him of his decision.

The move was a bitter blow to the PM who had long believed his old rival from their days at Eton and Oxford would ultimately fall in behind his EU re-negotiation package.

Minutes after Johnson’s news conference the bookmaker’s William Hill slashed their odds for the Leave campaign winning down from 5/2 to 7/4, while the odds of Johnson becoming the next Tory leader were also cut from 4/1 to 5/2 making him the joint favourite with George Osborne.

Reacting to the news, Ukip MP Douglas Carswell Tweeted: “It is magnificent news for the Leave campaign that Boris and Michael Gove are with us! Game changer”.

Last night an SNP source said: “All along Cameron’s EU ‘deal’ has been about trying to win on the home front – and lay to rest the infighting on the government benches at Westminster.

“But it’s been a lose-lose outcome for the Tory PM – he’s lost friends and influence in Europe while his own senior MPs and ministers are off to campaign to leave the EU.”

Johnson said Cameron’s re-negotiation had failed to deliver fundamental change in Britain’s relationship with Brussels.

“I don’t think that anybody can claim that this is fundamental reform of the EU or of Britain’s relationship with the EU,” he said.

“The last thing I wanted was to go against David Cameron or the Government but after a great deal of heartache I don’t think there is anything else I can do,” he said.

“I will be advocating vote leave ... because I want a better deal for the people of this country to save them money and to take back control.”

Earlier, Cameron had issued a last ditch appeal for the London Mayor not to align himself with “outers” like Ukip leader Nigel Farage and Respect’s George Galloway.

“I think the prospect of linking arms with Nigel Farage and George Galloway and taking a leap into the dark is the wrong step for our country,” he said.

“If Boris and if others really care about being able to get things done in our world, then the EU is one of the ways in which we get them done.”

Johnson said that he had decided to act because the European “political project” was “in danger of getting out of proper democratic control”.

“Sovereignty is people’s ability – the ability of the public – to control lives and to make sure that the people they elect are able to pass the laws that matter to them. The trouble is, with Europe that is being very greatly eroded,” he said.

“You have got a supreme judicial body in the European Court of Justice that projects down on this 500 million-people territory a single unified judicial order from which there is absolutely no recourse.

“In my view, that has been getting out of control. There is too much judicial activism – there is too much legislation coming from the EU.”

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