Chic cheerful

Today's look is light years removed from the immaculately suited and coiffed estate agent of a new romantic comedy Populaire, which opens the Glasgow Film Festival later this week. On screen Duris appears the epitome of the dashing romantic 1950s hero who coaches his young secretary and protegee (Deborah Francois looking like Grace Kelly) to hammer away on the keyboard to become the fastest typist in the universe. The competition is cut-throat and the contests, which were a la mode at the time, are filmed as if they were Olympian sporting events. Duris, despite his current grungy look, loved the period, the clothes and the style.

"It was like going into a little time warp when we started the shoot," he says, preferring to stick to French rather than struggle in English. "It was a very distinct and strong period in visual terms – just look at the Mad Men effect.

"I had seen the films with people like Cary Grant and James Stewart from that period but I watched them all again and also some of the French classics by Marcel Carne and Claude Chabrol. I wanted to nail the difference between the provinces and Paris, which was more apparent then, and the ways of behaving and speaking."

Duris's choices are always made on the basis of the quality of the script. He doesn't care whether the director is known or not – Populaire is the impressive debut feature by writer and director Regis Roinsard.

"When I read any script I need to be transported somewhere else. Either I identify with the character and situations right away or not at all. After that I need to know exactly what is the director's take on the project – and why he wants to make it.

"My main concern here was whether the costumes and the style might take over and it would be stuck in the past. We needed to make it feel live and real."

Duris's attitude to acting is that you do not learn it – he never attended drama school. "I would have been scared of the lessons because I am allergic to technicality," he admits. "The most important teacher is life, the things you come across as you go through it, including the sadness and the happiness. I have learned on the job, which is an opportunity few people can have. The downside is you can see all the mistakes and the defects but I have never known any other way."

Duris, 38, has been making his mark recently with a newly found mature confidence, whether it has been as the son of a slum landlord wanting to be a concert pianist in The Beat That My Heart Skipped by Jacques Audiard (a nominee for Best Actor in the Cesars, the French equivalent of the Oscars), the arch seducer in the huge hit Heartbreaker with Vanessa Paradis or the lawyer who murders his wife's lover in The Big Picture with Catherine Deneuve.

It took him a while to decide that acting was for him. He was spotted by chance and literally picked off the street by a casting director looking for teenagers for his eventual mentor Cedric Klapisch's first film Le Peril Jeune. At the time Duris was at university completing an arts degree, spending his spare moments as a drummer in a band and doing summer jobs such as delivering pizzas. He declared himself uncomfortable with all the attention that ensued after the release of Le Peril Jeune, which became a cult hit for his generation. He has long since stopped going on the Metro because he didn't like all the stares and bought a motorbike instead. Now he knows how to blend into the background and be hidden. His easygoing exterior meant people assumed he would be their friend. "It's just a question of attitude," he says.

When he was 18 he thought painting would be his "reason to live", but cinema took its place. "I still paint but it is a question of motivation and I can be very lazy, so I have put it to one side," he says.

Has he become more relaxed now about practising his profession? "No, I always have plenty of room for doubts, which are there constantly. I guess since my first film I have gradually begun to see what works and what doesn't, and that gives me a certain confidence. The more confident you are, the more risks you are prepared to take."

His association with Klapisch has been hugely influential and they continue to work together. After Le Peril Jeune, he made L'Auberge Espanol (which was released in the UK as Pot Luck) and its companion piece Les Poupees Russes (Russian Dolls). He played a naive economics graduate student studying for a year in Barcelona, as part of the Erasmus programme, where he encountered and learned from a group of students from all over Europe. Again he captured the mood of a generation, but it was only after this film he realised he had found his vocation rather than just doing a job. He has reprised his character of Xavier again recently for the third in the series, Casse-tete Chinois (Chinese Puzzle) recently filmed in New York. Xavier is now 40 and he follows his high-flying wife Wendy (Kelly Reilly) with their two children to her new financial job in the Big Apple.

"Because Cedric and I are friends, our working relationship has developed quite naturally," he suggests. "We work apart but we also come back to work together. We have to strive hard to maintain the same spontaneity and freshness that was there in the beginning, but maturity has brought something deeper."

Besides the new Klapisch film, which features his contemporary Audrey Tautou (who was his sugar-sweet girlfriend in L'Auberge Espanol) he has been working with Michel Gondry on his adaptation of Boris Vian's L'Ecume Des Jours – literally The Foam Of The Days but now known as Mood Indigo. He and Tautou (again) play two of the four lovers with curious compulsions alongside Untouchable's Omar Sy.

Duris keeps his family life discreetly in the background. His long-term partner is the French actress Olivia Bonamy with whom he has a four-year-son Luigi, and they live in the trendy Marais area with a much-loved golden labrador. His circle of close friends includes actors Melvil Poupaud and Elodie Bouchez and director Tony Gatlif with whom he has worked on several occasions.

At home his son claims centre stage, whereas when Duris was growing up he had to compete with his older siblings for parental attention – his father worked as an engineer and architect and his mother was a dancer. His sister Caroline is a concert pianist and she helped coach him for his piano playing in The Beat That My Heart Skipped while his brother Francois works as a designer with the car maker Peugeot (and has been helping Gondry with the period vehicles in Mood Indigo).

"Because I was the youngest I had to shout to get noticed," Duris says rather loudly. He was a bit of show-off and an extrovert, which doubtless helped with "playing" as an adult. He grew up without a television in the house and so far he has held out against one at home. To relax he watches tennis online.

"My parents taught me a valuable lesson: that it is very easy to be defined by what you do and to feel reassured when everyone likes you and finds what you do is great. If you go down that route, it is difficult to reinvent yourself. Often I'll refuse go on television simply because I want to ration myself. People don't understand but it's the only way to keep sane."

Populaire opens the Glasgow Film Festival at GFT on Thursday at 7.30pm and 8.15pm, followed by another screening on Friday at 1pm. The film is released UK-wide later in the year. Richard Mowe interviewed Romain Duris during the 15th Rendez-vous With French Cinema.