Britain's prime minister David Cameron has predicted a "Remain dividend" with an investment surge into Britain if the country votes on Thursday to stay in the EU. But he admitted: "It's very close, nobody knows what's going to happen."

More than 1,000 company bosses have signed a letter warning a Brexit vote would "put jobs at risk", but Mr Cameron said he was "frustrated" that more business executives had not publicly supported EU membership in recent weeks.

Speaking ahead of a vote that could determine his own future as well as Britain’s place in the world, he said voters could expect to see immediate benefits if they voted Remain. “I think on Friday that businesses, wealth creators, job creators will think: Britain has made a decision, let’s pile back into the economy and create jobs and opportunity because it’s a great place to do business,” he said.

Older voters

Mr Cameron urged older voters to “think about the hopes and dreams of your children and grandchildren”, in an attempt to inject an emotional element into the poll. Opinion surveys have consistently shown older voters siding with Leave while the young largely support continued EU membership.

The prime minister said there was no turning back from a Brexit vote. "If we vote to leave, this really is irreversible," he said, adding that future generations would have to live with the result.

Uncertainty

The Remain camp is mobilising a vast ground operation to “get out the vote”, hoping the combined efforts of nearly all mainstream UK political parties – Conservative,

Labour

, Liberal Democrat, SNP and

Greens

– and other activists can push up the turnout.

Despite the uncertainty, Mr Cameron insisted he was right to hold the referendum early in this parliament because there was “always going to be a Brexit chill” over the economy until the issue was settled. In a warning to his own Conservative MPs who say they will continue to fight for Brexit if Remain only wins by a narrow majority, he said: “As far as I’m concerned this referendum should settle the matter.”

He said he would “rapidly” begin exit talks with the EU in the event of a Leave vote by activating article 50 of the Lisbon Treaty, which formally begins two-year divorce proceedings.

– (Copyright The Financial Times Limited 2016)