You recognise the smile immediately. Daniel Cohn-Bendit’s face may show the lines of 61 years, his hair is no longer the burning red of 1968, but the smile facing me across the table is the same elfin grin which confronted the city’s riot police: the iconic picture that defined the Paris student uprising.

Dany le Rouge has long since transformed himself into Dany le Vert, the highest-profile Green politician on a continent that has suddenly embraced the cause he has proclaimed for most of his adult life. He is a rare example of a truly European politician; he says he is fulfilled. But talk to the generation for whom Dany’s authority-defying grin symbolised hope of a new beginning (not to mention free sex) and you’ll find a certain melancholy that he now plies his trade in the European parliament, viewed by some as one of the most boring institutions on earth.

So how did Cohn-Bendit get from the barricades to the air-conditioned corridors of the European parliament, and why is he enjoying it so much? Tony Blair seemed to be asking himself the same question in 2005 when he faced Cohn-Bendit in Brussels. After listening to a good-natured harangue of his European policies, the UK prime minister turned to his Franco-German tormentor and joked: ”I used to read his speeches; now he has to listen to mine. History will judge whether that is progress.”

Such is Cohn-Bendit’s love of the European parliament it proves fiendishly difficult to get him out of the building. After much negotiation, the FT’s lunch guest agrees to swap the parliament’s sedate members’ restaurant for the Quartier Leopold, a sleek and suity establishment nearby.

It is a faintly soulless place, as befits its name. The quartier Leopold used to be one of Brussels’ most opulent art nouveau neighbourhoods, until the EU moved in, when its maisons de maitre were demolished and replaced by faceless office blocks.

Cohn-Bendit admits he prefers the restaurant in the evening, when the Place du Luxembourg heaves with politicians, journalists, lawyers and interns in a heady, international mix of politics and sexual frisson. Was it a bit like that on the streets of Paris in May 1968, I wonder? ”It was absolutely fun,” says Cohn-Bendit, whose efforts to gain male student access to the girls’ dormitories was one of the sparks for the revolt. ”You felt for the first time you were turning the screw, you were not being turned by the screwdriver. It gave you a feeling of omnipotence.”

How much of it was about sex? Cohn-Bendit says this was a fixation of ”sex-alienated people” at the time. ”The truth was, we were arranging our lives and bodies, and developing how we wanted to live.” I ask him to elaborate. ”It was a very emotional situation. A lot of people discovered themselves and had new relationships. The mythology of the sex was because it was a completely closed society.”

By now the stylish waitress is hovering. Cohn-Bendit peruses the simple menu and opts for spring rolls and a scampi brochette. I go for gravadlax of salmon followed by red tuna. Disappointingly, he wants to drink nothing stronger than water, but as I discover, Cohn-Bendit does not need alcohol to hit his stride. Dressed in his trademark ”university lecturer” look of white T-shirt, open-necked blue shirt, mauve sweater and blue jacket, there is no holding him back. ”I was a symbol of the beginning,” he says, returning to the gas-filled streets of Nanterre in 1968. ”I was the sunshine. For a lot of people I was the perfect projection of the good part of the revolt.” He pulls his phone from his pocket, and shows me the iconic ”grin” picture. ”My son found it on the internet and sent it to me,” he says. ”For many people I was the smile of the time.”

For Cohn-Bendit, it was the liberation of the individual that was the most important legacy of the ”evenements” that rocked France and captivated the world. But what did he mean when he said the students had ”won socially and lost politically”? He explains: ”We thought we could invent a more radical, better structure than parliamentary democracy. Today I think this is wrong. But we opened the door. Our modern society recognised that individual freedom was something which has to be strengthened. It was a great time and now life goes on.”

His boyish enthusiasm still burns as he recalls how he was expelled from France to Germany, amid dark mutterings from the authorities about how he, a German Jew, was trying to destabilise the country. ”When it became clear I was forbidden to go back, there were 80,000 people on the streets shouting: ’We are all German Jews.’”

Back in Frankfurt, he disappeared from the headlines and started hanging out with Joschka Fischer, who went on to become Green foreign minister of Germany. Or, as Cohn-Bendit immediately corrects me: ”Joschka Fischer started hanging out with me.” This was his ”anarcho-leftist” phase, but he says he had no time for the violent wing of the movement, such as the Red Army Faction. He mischievously describes his decision to steer clear of the balaclava brigade as a lifestyle choice. ”The way of life attached to a guerrilla strategy is not a life,” he sighs. ”I never wanted to be a terrorist or a minister. Lifestyle is an important issue. If you are a terrorist you are dealing with the life or death of people, whether you have the right to kill - that to me is completely mad.

”Being a minister is not the same, but it’s definitely bad. OK, Joschka Fischer had a lot of power. But it’s a terrible life being foreign minister - you don’t know who you are or where you are.” Cohn-Bendit says he spoke to Fischer earlier in the day, and says his old friend is writing a book about his time in Gerhard Schroder’s Red-Green coalition. ”It will be really funny and a bit difficult for Schroder,” he laughs. In retrospect it seems obvious that Cohn-Bendit should end his spell in Frankfurt (he ran a kindergarten, a bookshop and ended up as deputy mayor) by re-emerging as a member of the European parliament. Everything about his past seemed to point in that direction.

Born in 1945 in Montauban, France, he is the son of German-Jewish parents who fled to France in 1933. With his German nationality and French identity, he embodies European reconciliation after the second world war. He was elected to the European parliament in 1994 in Germany, then in 1999 became the first MEP to be elected in another country when he fought the campaign in France. In 2004 he effortlessly returned to stand again in Germany. ”I wanted to demonstrate my double identity, my whole story,” he says. Fair enough, but why the European parliament? For all its legislative power, much of its work is mind-numbingly technical; it is a place of stilted debates in an often empty chamber, with little in the way of career prospects.

I’ve hit a nerve. Cohn-Bendit doesn’t recognise this description at all and starts twirling his arms with enthusiasm as he describes the experience of working in the world’s first truly international parliament. ”It’s a European environment that you find nowhere else,” he enthuses. ”You see how Europeans think, you have to find majorities. I find national parliaments boring. In the European parliament we are doing history. It’s a completely new sort of politics. In 50 or 100 years, historians will analyse all the moves of the European parliament, looking at how we started the debate on a European foreign policy, climate change or the social regulation of globalisation.”

But isn’t it a shame that so few people in the outside world seem to be paying attention when he makes his pyrotechnic interventions? (As Tony Blair discovered, Cohn-Bendit’s rhetorical style is equivalent to Black Sabbath turning up at a chamber- music recital.) He shrugs. At least he has five minutes to make his point to visiting prime ministers like Blair or Germany’s Angela Merkel. And his status as an MEP gives him a platform to speak around Europe, promoting his Green agenda - which has suddenly gone mainstream. I ask whether this sudden fashionability is a problem for the Greens. Now that even David Cameron, leader of the British Conservatives, is going on about climate change and visiting ice floes, doesn’t that make his party somewhat redundant?

Cohn-Bendit, officially the co-leader of the parliament’s Green group, sighs. ”Five years ago people said to me that the Greens were finished because nobody cared about ecology. Now they’re saying everyone’s interested in ecology, so the Greens will die.” He believes Europe should take a global lead in fighting climate change. ”You can see it,” he says. ”You can’t look at something like New Orleans and say ’shit happens.’ It’s just a fact.”

As we order coffees, I ask whether he enjoyed the scampi and ponder what exactly was the green puree on which they were embedded? ”I don’t know,” he admits, guessing perhaps peas, or avocado. He tastes the remnants on his plate, but is still none the wiser. ”Can I look at your menu?” he says to a neighbouring table.

Not a good sign, and I confess to him that my gravadlax was a little heavy on the mustard sauce and the tuna - like him - was not quite as rouge as advertised. No matter. Restaurants like Quartier Leopold are never going to be short of business so long as the EU is whirring away around the corner.

The coffees arrive and I judge this perhaps the right moment to ask the difficult question of whether he regrets writing Le Grand Bazar, the book that gave his critics the chance to portray him as a paedophile. In this 1976 work, exhumed by his political enemies 25 years later, Cohn-Bendit talks about children in his Frankfurt kindergarten opening his flies and tickling him. ”I asked them... ’Why have you chosen me, and not the other kids?’” he wrote. ”But if they insisted, I caressed them even so.”

I needn’t have worried about Cohn-Bendit storming out. The smile is set at maximum intensity: ”In those times a lot of people, including me, wrote some foolish things. Provocation was an ideology.” He says nobody batted an eyelid when the book came out, and it should be seen as ”a crazy sign of the times”. The storm, which might have finished some politicians, blew over. Parents of the kindergarten mounted a campaign in his defence. He seems almost to embrace the affair as having added just another stratum to his multi-layered life.”You have to stand by your history,” he says.

As he prepares to head out into the grey Brussels afternoon, he suddenly thrusts his phone into my hand. Out of the earpiece Edith Piaf is warbling Dany le Rouge’s theme tune: ”Non, Je Ne Regrette Rien”.

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Quartier Leopold, Brussels

1 x spring rolls

1 x salmon gravadlax

1 x brochette of prawns with mixed herbs

1 x red tuna and mushrooms

2 x mineral water

2 x espresso

Total: €64.10