Video reveals Boris Johnson said he would vote to 'stay' in the EU in 2013

The former London mayor said he was "in favour of the single market"

Boris Johnson, Brexit, interview, London mayor, Remain, Leave, UK, opinion polls

Boris Johnson addresses supporters in Norwich, campaigning on behalf of the Vote Leave | Image: Stefan Rousseau / PA Wire/Press Association Images

As Britain gears up for a vote on whether or not to leave the European Union, Leave campaigner Boris Johnson said in an interview in 2013 that he would vote to stay in the single market, it has emerged.

Asked by a journalist how he would vote if there was a referendum, Mr Johnson said: "I'd vote to stay in the single market. I'm in favour of the single market."

He added: "I want us to trade freely with our European friends and partners."

The interview contradicts the stance of the former London mayor throughout the referendum campaign.

Writing in the Sun on Sunday today, Mr Johnson said: "This is a once-in-a-lifetime chance to take back control of our democracy from an unelected, undemocratic, unaccountable and unreformed European Union."

"We are working flat out to achieve this. It's a chance to take back control of huge sums of money and to take back control our trade policy. There's a massive opportunity for Britain. We should be full of excitement and hope about what can be achieved."

Meanwhile, British Prime Minister David Cameron has warned voters against a "one-way ticket" out of the EU, saying there would be "no turning back" from a Leave vote.

He said the Leave campaign's dismissal of experts warning against Brexit is like ignoring the safety advice of a car mechanic.

"If you were about to get into your family car and drive your family at high speed on a motorway and the mechanic said to you, 'The brakes are faulty, the fuel is leaking, don't get in that car', you would listen to that expert," he said.

"Would you take a risk with your family and get into a faulty car? You wouldn't."

Mixed polls

As campaigning in the EU referendum resumes, a poll carried out following the death of MP Jo Cox suggests the Remain campaign has opened up a three-point lead.

A survey for The Mail on Sunday, carried out on June 17th and 18th, put Remain back in the lead on 45%, three points ahead of Leave on 42%.

A BMG telephone poll for the UK Herald, between June 10th and 15th, put Remain ahead on 46% with Leave on 43%, and 11% undecided or unwilling to say.

However, other opinion polls showed a mixture of results just days before the EU vote.

YouGov for the UK Sunday Times put Remain on 44%, one point ahead of Leave on 43% in a poll on June 16th and 17th.

ComRes for The Sunday People and The Independent has 44% saying they would be "delighted" with an Out vote compared to just 28% who would feel the same way about In.

Opinium for The Observer put the two sides level pegging on 44% - with Leave up two points on last week while Remain was unchanged.

The campaigns were suspended following the death of MP Jo Cox on Thursday, a killing that sparked discussion over the increasingly harsh tone of the debate.