Writing in The Daily Mail he warned: “Europe still has reason to fear a Le Pen presidency.

“It could be even more destabilising than Donald Trump’s tenure in the White House.

“Le Pen’s particular brand of economic nationalism means she thinks French citizens should have priority for access to welfare, jobs, housing and healthcare, which is against EU rules and is designed to be anti-immigrant.

“She wants French law to be superior to EU law and to cut French contributions to Brussels. All that spells chaos and crisis for the EU if she was ever in a position to deliver.”

While French opinion polls have shown Emmanuel Macron leading in the first round they have also shown that a hypothetical Macron v Le Pen second round could be very narrow and even lead to a Le Pen victory.

According to the latest Harris-Toluna survey, Macron is set to come out on top in the first round on 27 percent, with Ms Le Pen snatching a close second on 24 percent.

However, Mr Neil has warned that should Le Pen take the Élysée Palace, she could pose a threat not just to the EU but also to Britain.

He said: “Britain has cause to fear, too. She is broadly pro-Russian and anti-American, so much so that she wants to pull France out of NATO.

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Mr Neil argues, in the past, left wing voters have rallied around right wing and centrist candidates to defeat the far right but this is less likely to happen this year maximising the possibility of a Le Pen victory.

He said: “Yet when it comes to economic populism, for the left-behind it ticks a lot of boxes. I mean, who wouldn’t want to be taxed for only 30 years of a lifetime’s work?

“If Boris Johnson is in trouble come the next general election I wouldn’t be surprised to see him raid the Le Pen policy box.

“It means Le Pen will pick up not just Zemmour votes in the second round but Left-wing votes, too.

“The leading candidate of the Left, Jean-Luc Melenchon, is an ageing, unreconstructed Marxist (and yet another Putin fan boy — what is it with these French politicians?).

“He is likely to come third tomorrow. Polls suggest many of his voters simply won’t vote in round two and those who do are more likely to vote Le Pen (whose economic policies are not that different from Melenchon’s) than Macron.

“This is significant. In the past, when mainstream politicians have faced a Le Pen in round two (Jacques Chirac in 2002, Macron in 2017) they’ve always been able to count on all the other parties to rally round to see off the hard-Right. Not in 2022.”