The number of voters who want Britain to pull out of the EU has risen to its highest point since the General Election.

A shock Mail on Sunday poll today shows the ‘Out’ campaign has opened up a six-point lead in the wake of the Paris massacre, Cologne sex attacks and Syrian migrant crisis. And if London Mayor Boris Johnson were to throw his weight behind an exit, as its supporters hope, the gap would widen to eight points.

Brexit reversal: The number of voters who want Britain to pull out of the EU has risen to its highest point since the General Election

The 53-47 support for severing ties with Brussels is almost a direct reversal of a survey from the same pollsters last May, which showed a 54-46 split in favour of staying in.

Today’s Survation poll is the first since David Cameron and EU chiefs last week effectively fired the starting gun for a referendum on the so-called ‘Brexit’ – possibly as soon as June.

The Prime Minister has made it clear he will fight hard to stay in the EU and hopes to win further concessions at a Brussels summit next month on curbing migrant benefits.

He can draw comfort from other aspects of the poll which show that it is believed a significant number of people who want to leave the EU may change their mind at the last minute – and there is evidence of wide support for his proposed package of EU reforms.

And the 53-47 split excludes undecided voters. If they are included, the picture is more nuanced with 42 per cent in favour of ‘leave’, 38 for ‘remain’ and 20 yet to make up their mind.

Terror crisis: Between 34 and 47 per cent say the Paris massacre (above, one of the victims), New Year sex attacks in Cologne, Syrian exodus and growth of the Calais migrant camp has made them more likely to vote to leave the EU

Mr Cameron received an additional boost last night after it emerged that Eurosceptic Minister Michael Gove is to snub the ‘Out’ campaign, known as ‘Leave,’ and back Mr Cameron’s vow to ‘Remain’. Three years ago Mr Gove, a close ally of Mr Cameron, said he would vote to leave the EU.

The poll indicates Mr Cameron needs all the help he can get, as the crises in Europe coincide with a steady rise in support for leaving the EU. Mr Cameron has argued that retaining our links with the EU will make it easier to tackle these issues: voters are not convinced.

Fear: Paris and Syria terror crisis has triggered a surge for the out vote in poll

Between 34 and 47 per cent say the Paris massacre, New Year sex attacks in Cologne, Syrian exodus and growth of the Calais migrant camp have made them more likely to vote to leave the EU. An average of nearly ten per cent say these events make them more likely to vote ‘In’.

On a more positive note for Downing Street, if Mr Cameron succeeds in clinching a deal with Brussels that includes restricting migrants’ benefits, he would win more support.

Nearly one in two say it would be a good deal, compared to one in five who say it would not be enough.

And the survey supports claims that the ‘fear factor’, concerning the consequences of Britain having to ‘go it alone’ outside the EU, may lead an 11th hour loss of nerve among some who would like to vote Leave. A total of 43 per cent say ‘Out’ supporters could change their mind come referendum day; only 28 per cent say ‘Remain’ supporters will have a similar loss of nerve.

Further evidence of the emotional factor is clear as the number who agree ‘my heart says Leave but my head says Remain’ is twice as large as those who say the opposite. Mr Cameron’s insistence that he will not resign if he loses the referendum is also endorsed by voters by a margin of 42 per cent to 33. Even one in five Labour supporters say he should not throw in the towel.

Survation polled 1,017 voters online on Friday and yesterday.

'Out' secret weapon would be Boris - if he'd lead them

If Boris Johnson plucked up the courage to lead the ‘Out’ campaign, he could help steer it to victory – and replace David Cameron in No 10 by the summer.

That is the tantalising prospect for the London Mayor, according to the Survation poll for The Mail on Sunday. It shows how the referendum could turn into a giant game of political poker for senior Tories trying to calculate how it will affect their chances of succeeding Mr Cameron as Prime Minister.

Mr Johnson has all but ruled himself out of backing the ‘Leave’ campaign. But if he did, according to the poll, he could add two points to the gap in favour of severing ties with Brussels. Publicly, Mr Cameron has insisted he will not resign if he loses the vote; in reality, most Ministers say he would have little choice but to stand down.

Leader: If Boris Johnson plucked up the courage to lead the ‘Out’ campaign, he could help steer it to victory – and replace David Cameron in No 10 by the summer

And when asked who should replace Mr Cameron if he does, Mr Johnson is the clear winner over chief rivals Theresa May and George Osborne. A total of 24 per cent opt for Boris, with 15 per cent for May and ten per cent for the Chancellor.

The gap in Mr Johnson’s favour is even more marked among Labour and Ukip supporters than among Conservatives. Among those who back Ukip, Johnson beats Osborne by a thumping eight to one.

Osborne’s low rating is emphasised when voters are asked whose opinion counts most in the referendum. Cameron comes top followed by Nigel Farage, Jeremy Corbyn, Johnson, May and Tony Blair. Osborne scores even lower than former Labour Home Secretary Alan Johnson.

PM’s latest coup? It’s Gove, Minister who once wanted to leave

Cabinet heavyweight Michael Gove has become the latest Tory eurosceptic to snub the campaign for Britain to quit the EU.

Three years ago Justice Secretary Mr Gove said that he would vote to cut Britain’s ties with Brussels. Now he has decided to support David Cameron and campaign to stay in.

His U-turn mirrors similar somersaults by Conservative Eurosceptics Philip Hammond and William Hague. And it is a setback to the ‘Leave’ campaign, which wanted to make use of Mr Gove’s formidable debating skills.

Friends of Mr Gove denied his switch showed hypocrisy, stating he had always said he could change his mind if the EU made concessions to the UK.

Asked in 2013 whether Britain should leave the EU if there were a referendum at that point, Mr Gove said: ‘Yes, I’m not happy with our position. But my preference is for a change in Britain’s relationship with the EU.’

Coup: Cabinet heavyweight Michael Gove (right) has become the latest Tory eurosceptic to snub the campaign for Britain to quit the EU. Now he has decided to support David Cameron (left) and campaign to stay in

The Leave campaign intend to turn their lack of a ‘big hitter’ to their advantage by claiming they are on the side of the people in a David versus Goliath battle.

Mr Cameron pulled off another coup last night when the Tory MP who led the ‘No’ campaign to stop Britain joining the euro announced he is to lead a new Conservative group to persuade voters to say ‘Yes’ to staying in the EU.

Former Minister Nick Herbert is to lead Conservatives For Reform In Europe. The PM’s allies claim his ‘poacher turned gamekeeper’ move is a major coup.

As chief executive of the anti-euro Business For Sterling group, Mr Herbert played a key role in the successful campaign to stop Britain joining the euro when Tony Blair was Prime Minister.

He denied claims by pro-euro supporters that he was an ‘anti Europe extremist’.

Mr Herbert, 52, said last night: ‘In a reformed EU, we can opt out of criminal justice and security arrangements that do not suit Britain, while taking part in those that keep us safe.’

Comment: So we can debate Trident, Jeremy. But why not EU?

By Kate Hoey, Co-Chair of Labour Leave campaign

The proverbial visitor from Mars arriving on Planet Earth could be forgiven for thinking that, when it comes to the thorny question of the UK’s place in the European Union, only one party matters.

Such is the sound and fury of the headlines on Tory splits, rows and debates that even seasoned Earth-dwellers might think David Cameron’s party had a monopoly on the issue.

But as the launch of the official Labour Leave campaign this week will show, they don’t.

With the pace now quickening towards the long-awaited referendum on our EU membership, the debate within my own party is just as vibrant – and active – as within the Tories.

Kate Hoey MP: Let’s open it up so we can hear what the rank-and-file membership say on this vital issue

Our current party policy is indeed to campaign to stay in the EU. Officially, we are all europhiles. But as Jeremy Corbyn knows, there are tens of thousands of Labour voters, and many party members to boot, who take the opposite view.

Unlike a gilded circle of europhiles at Westminster, they have no love for Brussels and would like nothing more than their country to break free.

I say Mr Corbyn knows this because he was one of those people himself. Although strangely muted since he became leader, his views as a backbench MP were impeccably Eurosceptic and he, along with a couple of dozen others, were on many occasions in the lobby recording a Eurosceptic vote.

But whereas Mr Cameron seems relaxed about letting his Ministers speak their minds and allowing his grassroots party members to participate, the Labour leader is so far refusing to follow suit.

We need to ask why.

Different views: 'Our current party policy is indeed to campaign to stay in the EU. Officially, we are all europhiles. But as Jeremy Corbyn knows, there are tens of thousands of Labour voters, and many party members to boot, who take the opposite view,' writes Kate Hoey

The new Labour leader is determined to democratise the Labour Party, and allow rank-and-file members to have their say.

This is exactly what we are now doing in relation to whether we change our policy on the replacement of the UK’s Trident nuclear deterrent.

Jeremy, a long-standing opponent of Trident, is inviting party members and supporters to have their say and make their views known. Fair enough, but if this new-found internal democracy is good enough for Trident, it is surely good enough for the EU.

Now, apparently, the Labour leader is being advised not to open up the EU debate internally, when the battle over Trident is not yet won.

Sorry, Jeremy, but this just won’t do. You can’t invoke the spirit of democracy when it suits, but then revert to old-style, smoke-filled rooms to make party policy when it is not convenient.

Open vote: Kate Hoey writes that Jeremy Corbyn should 'show you are genuinely committed to democratising our party and ask our members what to do about the EU'

So as the national debate on the EU begins in earnest, my challenge to my leader is this: use the same open, democratic approach on whether we stay or leave the EU as you are doing with Trident. Let’s open it up so we can hear what the rank-and-file membership say on this vital issue.

For far too long, we’ve let the ‘bien pensant’ europhiles at the top of our party dictate Labour’s approach to the EU, regardless of what many party members may think. I don’t predict that a majority of party activists will side with me and agree that the UK would on balance be better off freed from the constraints and red tape of Brussels.

But I do forecast that the Labour membership is not some cosy, uniform pro-EU bloc but – rather like the Tories – we’re a party alive with different views on this most critical of questions.

So Jeremy, have the courage of your convictions: show you are genuinely committed to democratising our party and ask our members what to do about the EU. That way, we can tell the world – and any visiting aliens – what Labour really thinks about our EU membership.