If Marine Le Pen wins France's presidential elections in May, all talk of punishing Britain for the outrage of Brexit will become irrelevant.

French diplomacy will pirouette overnight under a National Front (FN) leader. The Élysée Palace will seek an Entente Cordiale with the British, offering a bilateral alliance on new foundations.

It will then be the European Union that faces an existential choice: whether to reinvent itself as a loose federation of nation states, or succumb to galloping disintegration

"What is the point in punishing a country? It is senseless, unless you think the EU is a prison, and you are condemned if you escape. I want to rebuild our damaged relations with the United Kingdom," she told the Daily Telegraph.

"A people decides its own destiny. You cannot force a country to do something that is against its own interests, or against the democratic process," she said.

It is a far cry from the language of President François Hollande, who told Europe that Britain must "pay a price" to deter any other country from toying with temptation.

Whether she has a chance of winning is hotly-disputed, but it is no longer unthinkable and the consequences are epochal. Bookmakers have lifted the odds to one in three as of February 13, an "alarming" development says Oxford Economics.

"France is the political heart of Europe, and the moment we leave the euro the whole project collapses," said Ms Le Pen. She leans across the table in her tiny office in the European Parliament with a glint of mischief.

French pollsters note her imperturbable serenity as the pillars of the French political system crumble around her, and the coronation of ex-premier François Fillon goes horribly awry. "She has established herself as an anchor of stability on the political landscape," says Frédéric Dabi from the polling group Ifop.

The latest L'Express poll found that she trails Mr Fillon by just 44 to 56 in a run-off election, nearing the margin of error in this ferbrile climate. The tabou of voting for the Front National is not what it was, and Britain's referendum shock has played into her hands.

"Brexit has been a powerful weapon for us. In the past our adversaries have always been able to say that there is 'no alternative' but now we have had Brexit, and then Trump, and Austria," she said.

"A whole psychological framework is breaking down. I think 2017 is going to be the year of the grand return of the nation state, the control of borders and currencies," she said.

David Fuller's view

Most articles mentioning Marine Le Pen dismiss her chances in this year’s elections because they are written for or quoted from the French establishment.  I think Ambrose Evans-Pritchard has a better perspective, partly because he is an original thinker and also a Francophile who is fluent in the language. 

While the consensus view is that Le Pen cannot win the Presidency in this year’s elections, I think she will at least do better than the polls suggest.  Why? 

1) Le Pen has made the Front National Party more acceptable and inclusive.  2) The mood in France has turned against the EU by 61 to 38 percent, second only to Greece (see graph if you can assess The Telegraph link above.)  3) Le Pen’s opponent in the second election will be pro-EU.  4) Le Pen is likely to win the first of this year’s French elections but she would need to gain over 50% of the vote to become President in this round.  That has never happened before and there are five candidates, of which only two will go through to the second round.  5) It is likely that some French voters are not declaring their preference to pollsters, as we also saw with Brexit and Trump’s Electoral College victory. 

 While a Le Pen presidency would certainly help the UK in its Brexit negotiations, Theresa May is likely to remain silent.  After all, it is France’s election.