After more than four decades making Oscar-winning films, Woody Allen has finally revealed his secret: it all comes down to the casting.

“The trick is to hire great people and let them do what they do. Don’t interfere with them too much, and then when they’re great, take credit for it.

“I’ve done this for many years and it works like a charm.”

Take his most recent outing: Midnight In Paris, which features a cameo from French first lady Carla Bruni as a tour guide. “My wife and I had brunch with the Sarkozys about a year and a half ago, and Carla was so beautiful and charming, so I said, ‘Would you ever think of being in a movie? Just for your own amusement’,” he recalls.

“She said, ‘Yes, just once in my life, I’d like to do it, so I could tell my grandchildren I was in a movie’. She was no problem, and very natural, given her showbusiness and theatrical background.”

The director’s 41st film is proof his formula works.

Already a box office hit in the States, the romantic comedy, with its star-studded cast of Owen Wilson, Rachel McAdams, Michael Sheen and Marion Cotillard, is a nostalgic love letter to the French capital, following Allen’s previous outings to Barcelona and London.

“I wanted it to be the way I saw Paris – through my eyes. I wanted it to look very beautiful,” says the 75-year-old, adjusting those iconic black frames.

The film follows writer Gil (Wilson), on holiday with his fiance Inez (McAdams) and her stuffy parents in Paris, while struggling to finish his first novel.

One evening, after declining an invitation from friends, he finds himself drunk and alone as bells chime midnight. A vintage car pulls up full of 1920s-style champagne drinkers and transports him back in time to a bar where he meets his cultural idols of yesteryear, including F Scott Fitzgerald (Tom Hiddleston), Salvador Dali (Adrien Brody) and Cole Porter (Yves Heck).

Inspiration took a while to strike, says Allen, who wrote and directed it: “I didn’t know what I was going to write. I knew I was going to write a film in Paris and I thought of the title, which suggests an enormous amount of romance,” he reveals.

“But months went by and I just couldn’t think of anything. Then it came to me.” Having received acclaim from both critics and fans, Allen readily admits Lady Luck was on his side: “I could have thought of something bad, or nothing at all and changed the title to something else.”

Allen, who counts Groucho Marx and Ingmar Bergman as his inspirations, rewrote the role of Gil especially for Wilson, switching the character from an “Eastern coast intellectual” into a laid-back Californian writer.

“Owen is the opposite of me. I am very New York, while he is west coast,” he explains. “He personifies that in his whole delivery. He’s relaxed and is a beach lover. It gives the character a whole different dimension.”

He had initial doubts about casting McAdams opposite Wilson, following their earlier appearance together in Wedding Crashers.

“I didn’t like the fact they had worked together in a picture before,” reveals Allen. “But I was certain I wanted Rachel. I saw her in the film and thought she was beautiful, sexy and funny, and I wanted to work with her.”

The New York film-maker has not appeared in his films since 2006’s Scoop but Allen is set to guest-star in his next comedy, The Bop Decameron, which is currently shooting in Rome. Made up of intertwining stories, it stars Jesse Eisenberg, Ellen Page, Penelope Cruz and Alec Baldwin.

“I can’t play the love interest any more and, of course, this is tremendously frustrating, because that’s really what I want to play,” he quips. “But, that’s not as believable anymore, so I have to play the backstage doorman at the theatre, or something like that.”

After his European jaunts, his heart remains close to home.

“I would love to make another film in New York, because there are a million things to do here and a million stories to tell,” he says.

Despite being well over retirement age, Allen – who has also written a one-act play, which opens on Broadway in October – isn’t planning on stashing away his director’s chair anytime soon.

“I’ve been working steadily since I was 16 years old. I’ve never stopped. I’ve never been unemployed,” he says.

“I consider myself extremely lucky. I’ve had nothing but good luck, everything I needed has come my way.”

* Midnight In Paris is released in cinemas on Friday, October 7