He vows to 'come off the fence with deafening éclat' when PM gets his deal

UK can survive outside EU because of booming exports to non-EU markets

Boris Johnson told voters today there is 'no reason to be afraid of' leaving the EU in a sign he is considering joining the Out campaign.

The outgoing Mayor of London insisted he would wait until David Cameron has finalised his deal with EU leaders at a crunch summit in Brussels at the end of this week before deciding whether to campaign for a Brexit.

But he promised to 'come off the fence with deafening éclat' when he decides which side of the EU referendum he will back.

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Boris Johnson, pictured on BBC One's Sunday Politics show today, hinted he could join the Out campaign by insisting there was 'no reason to be afraid' of voting for Brexit

Keeping his options open in an interview today, Mr Johnson said Britain would survive outside of the EU because of the increasing number of its exports going to non-EU countries.

JUST ONE IN FIVE VOTERS BELIEVE THE PM WILL GET A GOOD EU DEAL Six in ten voters have no faith in David Cameron, pictured, getting a good deal from the EU this week Just one in five voters believe David Cameron will bring back a deal that is good for Britain when he travels to Brussels for his crunch Brussels summit this week. Six in ten believe he will fail, according to a ComRes poll for the Independent on Sunday. A week after Mr Cameron warned that a Brexit could see thousands of migrants arriving from Calais 'overnight', the poll finds that 47 per cent of Brits believe Britain would be better able to manage migrants trying to come to the UK from Calais if it left the EU, Just 29 per cent believe Britain would best be able to manage migration by staying in the EU. And in a blow to Mr Cameron's personal ratings, less than a third of people now look on him favourably - a drop of seven points in the last three months. Advertisement

'I'm going to wait until the Prime Minister does his deal and I will then come off the fence with deafening eclat; whatever happens you will hear a lot from me,' he told the BBC. 'You don't have long to wait.

'The salient point is this: London is now doing unbelievably well.

'People thinking about Britain in Europe, Britain out of Europe should recognise that a lot of the investment we attract now is from places outside the EU.

'We export increasingly outside the EU. There is no reason to be afraid.'

Mr Johnson, who is stepping down as Mayor of London in May, insisted the capital would 'flourish' in or out of the EU.

'London is by far and away the economic powerhouse of the whole of Europe,' he said.

'It is the commercial, the financial, the cultural, the tech centre of the whole community, it is 25 per cent of UK GDP, it will flourish in or out - that is certainly the case.'

His message was notably different from Foreign Secretary Philip Hammond, who warned voters this morning that the EU could fall apart if Britain votes to leave.

He predicted the 'contagion' of Britain quitting the EU would spread to other member states and said the UK would only be able to watch from the sidelines as the EU 'lurches in very much the wrong direction'.

'What I think I fear and many people in Europe fear is that without Britain Europe would lurch in very much the wrong direction,' he told the Andrew Marr Show.

'Britain has been an enormously important influence in Europe, an influence for open markets for free trade.

'I think we would be dealing with a Europe that looked very much less in our image. I think the thing we have to remember is that there is a real fear in Europe that if Britain leaves the contagion will spread.'

His comments come as a new poll today finds six in ten voters have no faith in David Cameron winning a good deal for Britain as he seeks to finalise his renegotiation at a crunch summit this week.

Just 21 per cent of the public expect David Cameron to get a good settlement in his reform package when he heads to Brussels on Thursday, according to a Comres survey for the Independent on Sunday.

Marina Wheeler, pictured with her husband Boris Johnson, last week wrote a damning legal assessment of the Prime Minister's draft proposals for reforming Britain's membership of the EU

David Cameron, pictured with Boris Johnson, knows that winning the backing of the London Mayor is crucial in his hope to keep Britain in the EU

Mr Hammond's intervention has caused further outrage among Eurosceptics, who are angry that Mr Cameron allows pro-EU ministers to speak in favour of staying in but is blocking anti-EU ministers from speaking out until after the Cabinet meets following this week's EU summit.

Graham Brady, the chairman of the influential 1922 committee of backbench Tory MPs, said it was crucial that the Government holds a Cabinet meeting as soon as possible after Mr Cameron returns from Brussels on Friday, when he hopes to have agreed a deal with EU leaders.

Number 10 said it was only during times of war that Cabinet met at the weekend, meaning ministers will have to wait until Monday to start campaigning for Brexit while pro-EU ministers are free to dominate the airwaves for 48 hours after the EU summit ends.

Mr Brady told Sky News: 'It's in everybody's interests to do this as quickly as possible.

Wheeler, pictured with her husband on polling day, said the European Court of Justice 'erodes sovereignty'

'If it were to appear that David Cameron was seeking to have the whole weekend to himself to put one side of the argument, I think that would look bad for the remaining campaign.

CRUNCH WEEK FOR BIG EU VOTE MONDAY David Cameron had called a crunch Cabinet meeting to fire up Ministers for the negotiations in Brussels – but has been forced to cancel it as too many of his senior team were out of the country. One sardonic source said: 'The most crucial Cabinet since the Election is scrapped due to skiing holidays.' TUESDAY The Prime Minister flies to the European Parliament to discuss his reform plans. He will to try to win politicians over as the Parliament is likely to vote on whether Britain is allowed to apply an 'emergency brake' on benefits to EU migrants. THURSDAY Today the talking will start in the Justus Lipsius building in Brussels. The draft agenda says the UK deal should be concluded over dinner. FRIDAY Friday is meant to be set aside for talks on migration. But sources acknowledge that UK negotiations might stretch into a second day. They could even be a 'three shirter', running into Saturday. Although diplomatic 'sherpas' have started talks, four of Britain's key demands remain in the air: the UK's wish to halt ever-closer union, protection from the eurozone block, the brake on benefits and curbs on child benefits for migrants. NEXT After the summit, the PM has pledged a Cabinet meeting, after which Ministers will be free to announce whether they back 'In' or 'Out'. No date has been set, but Mr Cameron is under pressure to hold it on Saturday. Advertisement

'People want an honest, fair debate. They want an honest, fair campaign, so I think it's in the interests of both sides to have that early cabinet meeting and to make sure that people who want to speak out and exploit the freedom of conscience that has rightly been agreed can do so as soon as possible.'

Mr Johnson's comments today are a further sign he will back the Brexit campaign.

Last week his wife savaged Mr Cameron's EU deal, writing a 2,700-word essay explaining why it fails to address the core legal problems of Britain's membership of the 28-state bloc.

In a damning assessment Marina Wheeler QC, a human rights lawyer, said they 'raise more questions than they answer'.

And on the key issue of sovereignty - the most important area for Mr Johnson - she said the plan for a 'red card' for national parliaments to veto unwanted EU laws 'ducks the issue entirely'.

Accusing Cameron of ignoring the real problems of Britain's membership of the EU, she wrote that 'proper reform' should address the way the EU enforces its legislation.

She said the Prime Minister's renegotiation should have reviewed the jurisdiction of the European Court of Justice, 'whose reach has extended to a point where the status quo is untenable'.

The ECJ is 'eroding national sovereignty,' she wrote and also 'undermines legal certainty' and 'good governance'.

Wheeler left open the possibility of backing Mr Cameron in the referendum but suggested she will only do so if he significantly broadens his demands for reform.

'Now, when Britain is debating its relationship to the EU, we should state our position afresh,' she wrote in an essay for the Human Rights Blog.

'Here is an opportunity to restore a measure of constitutional coherence. Let us not pass it by.'