Brexit decision on European Union final, warns Cameron

David Cameron has warned that a decision to leave the European Union in this week's referendum will be irreversible, with no prospect of Britain rejoining in future.

He warned that, if Britain regrets its decision to leave and seeks to rejoin the EU, it would be obliged, like other new entrants, to adopt the euro and join the Schengen open borders system.

“This is a final, irreversible decision. There is no going back when you walk through that door,” he said.

The prime minister was speaking during a special edition on the BBC's Question Time, during which he faced tough questions from a studio audience.

Campaigning in the referendum resumed on Sunday after a three-day suspension following Thursday's murder of Labour MP Jo Cox. MPs will pay tribute to Ms Cox in the House of Commons today after parliament was recalled in response to the killing.

Thomas Mair (52) who was charged on Saturday with Ms Cox's murder, gave his name to the court as "Death to traitors, freedom for Britain".

Polling data

Mair, who is from Birstall in West Yorkshire, where the 41-year-old mother of two was shot and stabbed outside her advice clinic, remained silent when asked his address and date of birth.

After more than a week of polls showing Leave opening up a significant lead, polls over the weekend offered better news for Remain, which was ahead in two out of four published on Sunday and tied in one. Supplementary questions in some polls suggested that voters were more concerned about the economic risks of Brexit than before and were drifting towards a vote to remain in the EU.

It is unclear if Ms Cox's murder has had an impact on voting intention, although Ukip leader Nigel Farage suggested that it could have halted the momentum behind the Leave campaign.

Momentum

“I think we have momentum – we did have momentum until this terrible tragedy,” he told ITV’s Robert Peston. “When you are taking on the establishment, you need to have momentum. I don’t know what is going to happen in the course of the next three or four days.”

On Question Time, Mr Cameron criticised a Ukip poster, which showed a queue of Syrian refugees at the Croatian border under the headline "Breaking Point".

Although the studio audience was evenly divided between supporters of Leave and remain, most of the questioning was hostile.

In a passionate exchange, when a questioner compared Mr Cameron’s EU renegotiation to Neville Chamberlain’s appeasement of Hitler, the prime minister invoked Winston Churchill.

“He didn’t quit. He didn’t quit on European democracy, he didn’t quit on European freedom . . . You can’t win a football match if you’re not on the pitch,” he said.