Is France still France? As a great independent nation, it seems to have vanished.

Here is a country with no control of its currency, no control of its borders and limited control of its defence.

It retains complete control of a collection of enormous and beautifully maintained monuments which serve as a reminder of past glories. But even as an occasional visitor, gazing on these wonders, one senses a certain vacuity. The people who animated these scenes with their faith, wit, intellect and arguments have departed, and we find ourselves contemplating a grand stage without grand actors.

For the French themselves, the situation is incomparably worse. Many of them feel they have lost their French identity, without acquiring a new European identity.

Perhaps the recent terrorist onslaught will precipitate the development of a confident and multi-racial France, dedicated to freedom. Already a great march has been held in Paris, intended to proclaim unity in the face of murderous attack, and attended by many foreign leaders, including David Cameron.

But Marine Le Pen, the leader of the Front National (FN), did not go on that march. She complained that the French President, François Hollande, had omitted to invite her when she saw him two days earlier.

This was a convenient excuse. If she and her followers had really wished to attend the rally, they could not have been kept away.

Instead Le Pen declared: “If I’m not invited, I’m not going to insist. It’s an old trap. The slightest incident and they’ll say it’s my fault.”

She preferred to retain her status as an outsider, a self-proclaimed victim who speaks up for others who feel themselves to be victims. Le Pen held a small rally in Beaucaire, a town with an FN Mayor, situated on the Rhone in southern France.

Here she gave a short speech to a crowd which proceeded to sing the Marseillaise and to chant “On est chez nous”: “Here we are at home”.

If the French establishment mishandles things over the next two years, something it has done with reckless frequency over the last two decades, Le Pen will be in a strong position to challenge for the presidency in 2017.

Ever since her father, Jean-Marie Le Pen, founded the FN in 1972, it has been the party which speaks up in a vulgar and xenophobic tone for the kind of disappointed French patriot who blames General de Gaulle for abandoning Algeria, and sees the good in Marshal Pétain for reaching an accommodation with Hitler.

Old man Le Pen’s crudity is conveyed by his jokes, of which a single example will suffice: “I bought a house in the country so my children who live in the 15th arrondissement [of Paris] can see cows instead of Arabs.”

He is still honorary President of the FN, and at the age of 86 continues with eloquent tastelessness to express the opinions of the FN rank and file: he denounced the leaders who went on Sunday’s march in Paris as “clowns responsible for the decadence of France”, and said they were also responsible for the terrorist attacks, for they had failed to oppose “insecurity, of which the origin is mass immigration”.

In 2002, Le Pen terrified the French establishment by reaching the second round of the presidential election. In order to stop him, everyone else including the Socialists voted for Jacques Chirac, who won by 82 per cent to 18.

In 2011, Le Pen the Elder handed over the leadership of the party to Marine, the youngest of his three daughters.

She was born in 1968, and when she was eight, the flat in the 15th arrondissement where the Le Pens were living was blown up with 20 kilogrammes of dynamite planted by an unknown hand. Somewhat surprisingly, neither they nor their neighbours were killed.

This frightening event forms the first chapter of Marine’s autobiography, A contre flots [Against the Current], a work written in the irritating style of someone who believes herself to be far more sensitive, and less inclined to self-pity, than she really is.

When Marine was 19, her mother, Pierrette, walked out on her father and took revenge on him by posing for photographs in Playboy. Marine devotes many pages to this excruciating episode, which is again used to try to coerce the reader’s sympathy. She herself has been married and divorced twice, has three children by her first husband and lives with Louis Aliot, a senior figure in the FN.

After leaving school, she qualified as a lawyer, and practised for a few years: among the clients she was obliged to represent were illegal immigrants. But at the age of 18 she joined the FN, and most of her life has been devoted to her father’s movement, and in recent years to its “de-demonisation”: the striking of a more moderate tone, which makes it harder to write her and her followers off as a band of repellent racists. In the words of Steve Briois, one of the FN’s rising stars, after he became Mayor of Hénin-Beaumont, a former mining town south of Lille, in March 2014: “We don’t eat children.”

Marine herself generally has better manners when talking to journalists, or appearing on television, than her father ever did. From 2002 she began to emerge as an accomplished television performer, who could attract larger than usual audiences to discussion programmes. In the 2012 presidential election she finished third, with nearly 18 per cent of the vote, and in the 2014 European elections, the FN topped the poll with almost 25 per cent.

As Patrick Marnham has pointed out, the FN tends to do best when fighting the Socialists, from whom it has had increasing success in detaching the shattered remnants of the white working class: though one should not deny President Hollande his share of the credit, or blame, for that achievement. Le Pen has devoted much time to campaigning in Nord-Pas-de-Calais, which has lost most of its traditional industry. She is more than capable of blaming immigration, and Muslims, for France’s ills, when it suits her, but more often finds it expedient to attack the European Union. France’s political class is condemned by her for selling out to Brussels. As she put it two months ago in a radio phone-in: “They have failed. They are bankrupt. They didn’t react for decades when our sovereignty passed into the hands of the European Union and we became a vast playground for the multinationals.”

The beauty of the European issue, from her point of view, is that it can be used to attack so many different targets: open borders, the immigrants who profit from those borders, the euro, the banks, the big corporations, globalisation, the United States, and the unwillingness of the French elite to put the interests of their own people first. Persistently high unemployment, which has done so much to undermine the popularity of Hollande and the Socialists, is far more difficult to overcome while France is confined to the straitjacket of the euro. In Britain, when things went wrong, the exchange rate took part of the strain: in France and the rest of the euro area, that couldn’t happen.

Le Pen has the courage, or effrontery, to confront a problem which her rivals still wish to suppress. She wants to leave the euro and reintroduce the franc, restore border controls (something she again demanded after last week’s terrorist attacks), reduce immigration by 90 per cent, assert the primacy of French law and introduce what she calls “intelligent protectionism”. She also favours withdrawal from NATO, a less subservient attitude toward the United States, and a Franco-Russian partnership: “I admire Vladimir Putin. He makes mistakes, but who doesn’t?”

She believes that leaving the euro can give France great leverage. As she put it when Ambrose Evans-Pritchard interviewed her in Nanterre, the FN’s headquarters, in June 2013: “The euro ceases to exist the moment that France leaves, and that is our incredible strength. What are they going to do, send in tanks?” She went on: “Europe is just a great bluff. On one side there is the immense power of sovereign peoples, and on the other side are a few technocrats.”

One might retort that Le Pen is just a great bluff. Whenever she and the FN start to do alarmingly well, the French establishment and a majority of French voters gang up on her. To many of the French, there is something intolerably embarrassing about the idea of being led by such a vulgar populist.

But one cannot say that vulgarity debars one from playing a leading role in French public life. If it did, Hollande’s predecessor, Nicolas Sarkozy, would never have become President. Although under investigation on corruption charges, Sarkozy with boundless impudence is now attempting a comeback, which could have the effect of further damaging the UMP, the main centre-right grouping, already grievously damaged by infighting.

What is a French voter of conservative disposition to do? This term, it should be noted, includes some Muslims, as Colin Randall reported last year from Fréjus, just after that Riviera resort had elected an FN Mayor. Karim, a 40-year-old Muslim who was born in France, was brought up in his parents’ native Algeria, and now works for the local council, assured Randall that he knew Muslims who had voted FN, but would not disclose whether he was among them, saying only: “The main left and right parties have failed them. But for many Muslims, the moves towards legalising gay marriage would be enough by itself to vote for a party like the FN that opposes it too.”

Le Pen repels at least as much as she attracts. She continues to be kept at a distance by many one might have expected to support her: Nigel Farage has declined to lead UKIP into an alliance with her. But the future of this gifted populist depends mainly on whether the conventional parties rise to the level of events, or whether they appear so impotent and corrupt that no one trusts them, and thwarted French patriots turn in desperation to the FN.