Some business leaders claim the prospect of Jeremy Corbyn becoming Prime Minister was making them far more fearful than Brexit.
This month, a Survation poll put Labour on 45 per cent, eight points ahead of the Tories – the biggest lead recorded in the last five months.
This has fuelled his supporters’ hopes that their leader could charge to victory should there be a snap election.
But City of London figures have voiced concerns over the policies of Mr Corbyn and his tough-talking Shadow Chancellor John McDonnell.
Labour has vowed to nationalise Britain’s railways, hike taxes and shift the Government’s priorities to low earners.
That has rattled some figures in big business and the City who fear an economic disaster.
Private equity investor Edi Truell told the Financial Times he had taken his £250 million family funds out of the UK because of his concerns.
He said: “I would be devastated if he got into power. It would be disastrous.
“I’ve heard from investors who say ‘we don’t want to invest in the UK, not because of Brexit but because of Corbyn’.”
And Endless private equity group manager Garry Wilson warned investors would stop sending some of their money to the UK if Corbyn seized power.
He told the paper: “A lot of investors are just hoping and praying it doesn’t happen.”
Others have warned the UK’s reliance on its tax base made it vulnerable if high earners started leaving the country.
But Dean Turner, an economist at UBS Wealth Management, said talk of Mr Corbyn’s danger to the country was “extreme”.
He said: “If we do see a weaker pound, the change would be gradual.
“I doubt we would see the kind of falls we saw post-Brexit vote.”
Last month, Morgan Stanley warned a Corbyn government would damage the valuation of UK companies and was more dangerous than Brexit.
Finance firm the CME Group also advised investors that a Labour government would contribute to a “nightmare scenario for the pound”.
But in response to Morgan Stanley, Mr Corbyn branded the big banks “speculators and gamblers who crashed our economy in 2008”.
In a social media video, he insisted: “Labour is a growing movement of well over half a million members and a government-in-waiting that will work for the many.
“So when they say we’re a threat, they’re right.
“We’re a threat to a damaging and failed system that’s rigged for the few.”