Everyone in France knows what is going through the head of Nicolas Sarkozy as he basks in the glory of a British royal welcome. For Super-Sarko, the supreme honours from the ancestral foe are delicious vindication. It is another shot in the eye for Jacques Chirac and the other elders who tried so long to thwart the ambition of the bumptious boy from Neuilly-sur-Seine.

We know this because no French leader, at least since Napoleonic days, has revealed so much about himself and offered such fuel for character analysis. François Mitterrand cultivated mystery and Mr Chirac kept a distance with the mask of a genial father-figure. But everyone, from psychiatrists to the man in the bistro, thinks they know what makes Sarko tick. Their diagnoses are unflattering and sometimes wildly unfair but the President bears the blame. Until lately, this product of the post-68 Me Generation has been unable to stop talking about himself. For years he cast himself as the fatherless outsider who would show 'em all that he could reach the top. France was then invited to share his emotions through his bumpy first months in office.

Since his party took a national hammering in town hall elections a fortnight ago, Mr Sarkozy has been persuaded to tone down his impulsive, exhibitionist nature and start acting with the detachment expected of the republican monarch. His popularity crashed, not because people resent his reforms, but because he lacked decorum, the polls showed. France remains more formal than Britain, which kept a chat show host as Prime Minister for a decade. It does not want a playboy who flaunts a trophy wife while telling a depressed people that he is powerless because “the treasury is empty”. It also does not want the holder of the nuclear trigger to be a hothead who insults the public. Sarko's televised “get lost, poor sod” to an unfriendly bystander last month cost him dear.

We now have a new, sober, subdued Sarko, a statesman rather than manic micromanager who dashes out to chat up trade union leaders at the brasserie. Out also are the clunky watches, the flaunting of Carla Bruni and the staged soap opera of his private life.

Le Sarko nouveau, however, runs against nature; and the word from the Elysée is that the boss is still not convinced that he got it wrong. He won the presidency last year by trusting his gut and shunning the experts who advised that his conservative country would never fall for an unabashed radical reformer promising la rupture.

The question is whether “Sarko season II” can live up to expectation. This is not the first time the former Gaullist has staged a makeover. He opened his election campaign last year announcing: “I have changed.” Selling a seductive vision of Gallic renaissance, he convinced voters that he had mellowed and was the man of destiny that France craves in its leaders.

Doubts about his judgment soon reappeared when Yasmina Reza published her fly-on-the-wall book about his campaign. The acerbic playwright did not depict the conquering hero that Sarko must have expected. She cast him as brave and dynamic but also as an insecure, boyish tantrum-thrower with a short attention span.

After the autumn departure of Cécilia, his last wife, Mr Sarkozy became more manic than ever and critics piled in. Media converts who had praised him in the spring began asking: “What were we thinking of?” The President then appeared to lose the thread as he indulged in his speedy courtship of Ms Bruni.

Since France loves psychoanalysis, the shrinks have had a field day. In books, seminars and television appearances they have described Sarko as neurotic, bipolar, Oedipal, even psychopathic. One psychiatrist, Hervé Hubert, has been running a popular seminar at Paris VII University with the title “Sarkozy the symptom: a reading of the unconscious”. His diagnosis is widely shared down at the pub. The vertically challenged President seeks the love of the public because his father abandoned him as a child; the swift replacement of Cécilia by Carla is a symptom of self-indulgence and insecurity, and so on.

Some of Sarko's old colleagues have joined the fray. François Léotard, a former Defence Minister, has published a book in which he detects in the President narcissism, aggression and childish behaviour that stem from insecurity. In another approach Jacques Alain Miller, a psychiatrist, told the President this week that his only hope for reforming himself was to undergo analysis. Sarko's problem is his inability to distinguish his ego from his id, Miller concluded.

But there is another way of looking at “Psycho Sarko”. The neurosis may not be on the President's side, but with the French and their mania with him. For months Super-Sarko has dominated conversation. The psychiatrists say their patients bring him up as soon as they hit the couch, so they have coined a new term - “acute Sarkozis”. This means being obsessed by the phenomenon of the President - le personnage mythologique - rather than the real man. From there it is only a small step to seeing that France may not know its President as well as it thinks.

The Windsor visit has helped Mr Sarkozy at the start of a long climb back to favour. The President is said to be in grim mood because the world economic slowdown threatens his efforts to jolt France out of its old habits. Yet it seems that Sarko really has calmed down. According to a report yesterday, François Fillon, the Prime Minister, gives credit to his new wife. Mr Fillon is supposed to have said: “We have entered a sort of routine. God bless Carla.”

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