How likely is it that François Fillon’s bid to be President of France will be derailed by the claim that his Welsh wife was paid close to half a million pounds out of public funds for falsely claiming to be his parliamentary assistant?

It doesn’t look good. That much is clear. But all that can be said for certain is that an investigation is under way,  led by state prosecutors. Fillon, the arch-Catholic conservative, whose front-runner status rests in large part on the perception of him as a man of the utmost probity, has expressed outrage at the suggestion in the satirical weekly Le Canard Enchainé that anything untoward has occured.

His wife, he said, who once told the Sunday Telegraph that she rarely went to Paris and took little interest in politics, was fully entitled to be paid for work legally carried out, and accusations to the contrary were fulled by “contempt and misogyny”.

Unsurprisingly, L’Équipe Fillon was in emergency session throughout the night, promising that their man would “very quickly” provide the necessary proof that Madame – the former Penelope Clarke, from Llanover, in deepest Monmouthshire – did not embezzle from the state but was in fact an integral, and hard-working, part of her husband’s constituency business.

The problem is that Le Canard has reportedly seen the relevant wage slips, indicating that for many years, until quite recently, the putative First Lady was one of the highest-paid, and least visible, assistantes in France. 

The article has been published, nailed to the Parisian media equivalent of Wittenberg parish church. But already the counter-reformation is underway. Having presented himself and his wife as the victims of a liberal witch hunt, Fillon will be hoping, like so many French political leaders before him, to outwit, and out-wait, his accusers.

And, if past expeience is anything to go by, he may just get away with it.

The French legal process, at its worst, can provide those awaiting its rulings with a reasonable apprehension of eternity. Fillon will in the meantime stand tall and resolute, like a tortured medieval saint.  Expect to see him at mass on Sunday, though not necessarily in the vicinity of the Confessional.

Political scandals in France rumble along. Like geothermal pools, they boil and bubble and give off foul smells. But almost never do they erupt with the kind of violence that in Britain or America would spell the end of a career.

François Mitterrand, Valéry Giscard d’Estaing, Jacques Chirac, Nicolas Sarkozy, Alain Juppé: they have all been defined to a greater or lesser extent by scandal. But they all got away with it.

Mitterrand simply rose above his legion of accusers, who never managed to lay a glove on him while he was alive. Giscard was accused  – also by Le Canard Enchainé – of accepting blood diamonds from the self-styled Emperor of Central Africa, Jean-Bédel Bokassa. Chirac, now thought to be terminally ill, avoided a custodial sentence after being convicted of fraud while mayor of Paris by persuading the court that he was too old and out of it to know what was happening. 

Sarkozy, whose recent attempted comeback was thwarted by voters tired of his preening pomposity, still faces charges of serious financial impropriety, but no one believes that he will ever be fitted out for an orange jump-suit.

Juppé, a former prime minister, sentenced to 18 months in prison for misusing public funds, never served a day behind bars and as recently as last November was considered the most likely candidate of the Centre-Right in this year’s presidential elections. His defeat by Fillon was the biggest political surprise in France for many years. 

Most recently, François Hollande gave up on the possibility of a second term in the Elysée not because he ditched both the mother of his children and her replacement and then embarked (on the back of a scooter) on an all-too public affair with an actress, but because he was a useless President. 

Fillon is a different kettle of fish. A  cultural throwback, whom it is possible to imagine wearing a top-hat and frock coat, he lives with his wife in a 12th century chateau of which, until now, she was believed to be the full-time chatelaine. He believes in the traditional teachings of the Church, as expounded by John Paul II rather than Pope Francis, and has promised his followers that France under his presidency will be both harder-working and more austere.

Should voters now desert him, believing him to be as corrupt as those he has so roundly excoriated, the impact will be considerable. In France itself, the role of heir-presumptive could pass from Fillon to either Emmanuel Macron, the 38-year-old technocrat firebrand, or just as plausibly, to Marine Le Pen, leader of the far-right Front National. 

Fillon has described himself as a Thatcherite; Macron is unabashedly Blairite. Le Pen channels Joan of Arc by way of Nigel Farage. Though stern by nature, Fillon would do his best to play fair by the UK in the Brexit negotiations – not least because of his wife’s avowedly Anglo-Welsh sensibilities. Macron, no enemy of Britain but less of an anglophile, could be relied on to turn Brexit to his advantage, using it as a stick with which to beat those Europeans opposed to change. Le Pen, of course, would play the nationalist card, pouring scorn on the EU and inviting its destruction. 

Fillon’s difficulty is Le Pen’s opportunity. Should he fall, to be replaced on the right by the septuagenarian (and shop-soiled) Juppé, only Macron will realistically stand between reason and revolution in France. Theresa May will join Fillon in praying that events do not come to such a pass.