Speaking on Sky News last night, the Prime Minister said he would trigger exit procedures immediately after a Brexit vote but claimed it would take 10 years to renegotiate trade deals with the European Union.
“Do we want a decade of uncertainty?” he asked.
Cameron also denied that he has tried to scare British voters over a potential Brexit.
In particular, he was pressed over a controversial government report claiming that leaving the EU would see households £4,300 worse off, which the Treasury Select Committee has dismissed as “a mistaken assertion.”
Cameron was also questioned by a member of the public on whether the tone of his campaign had damaged his legacy.
“I think there are real risks from leaving. I don’t accept it’s scaremongering. I am genuinely worried about Britain leaving the single market,” he said.
Vote Leave chief executive Matthew Elliot said the debate “showed the public doesn’t trust Cameron.”
The Prime Minister also refuted arguments that rulings from the European Court of Justice have the effect of undermining UK sovereignty.
In a combative session with Sky News' Faisal Islam, the Prime Minister also rejected suggestions that the European Court of Justice undermines the UK sovereignty, in particular because of its moves to raise VAT on specific items, after a Conservative election promise of limit increases.
The Conservatives 2015 manifesto included a pledge to avoid raising VAT, or extending its' breadth, but Cameron maintained that his government had not broken its promise, arguing that it reflected only the main rate of VAT.
And he denied that this represented the sovereignty of the European Union over British governments.
“If you are in a single market, you need single rules. But this means we are part of the single market,” he said.
However, the Prime Minister also acknowledged his frustrations with the EU.
“Is it imperfect? Do I find it frustrating as someone who is sceptical about these grand schemes and visions? Of course I do,” Cameron said.
“Sometimes this organisation drives me crazy.”