The French film director Olivier Assayas is sitting in London’s Mayfair hotel, reflecting on the Cannes Film Festival. Last year, his latest film Personal Shopper split the critics – gaining as many five-star raves as one-star trashings. Then he won Best Director. “Cannes is a strange place,” he muses. “It’s a place where the press feel guilty, because they spend two weeks partying, drinking, going from cocktail [party] to cocktail [party]. And they feel as bad about it [so] they want to have social movies about how people suffer in the world... and I don’t make social movies.”

A former critic for Cahiers du cinema, Assayas, 62, arguably knows what he’s talking about when it comes to film journalists. Same goes for the industry. He may be married to fellow French director Mia Hansen-Løve (with whom he has one daughter), but Assayas believes he’s only on the fringes of his nation’s independent cinema scene. “I created a space of my own where I make multi-national films,“ he explains. His last film, Clouds of Sils Maria, also starred Kristen Stewart, who became the first non-French actress ever to win a French César award for her performance.

As a result, he was all set to make Idol’s Eye, a 1970s-Chicago true-crime thriller with Robert De Niro and Robert Pattinson until it collapsed the day before shooting was due to begin. “It was frustrating,” he says, his voice betraying none of the heartache that must’ve caused. Instead, he came back to Paris “and started from scratch”, writing Personal Shopper, a ghost story set in the world of high-fashion. Again, his leading lady is former Twilight star Kristen Stewart, who states she loves Assayas’s work because he makes films “that don’t always have to answer every question for you”.

The former 'Twilight' star Stewart plays Maureen who finds haute couture outfits for her German supermodel boss

The appreciation is certainly mutual. Assayas calls Stewart “the best actress of her generation” and his bond with the 27 year-old is strong. “Ultimately I don’t think I would’ve written this screenplay if I had not known Kristen,” he adds. “It’s more like she inspired it.” She plays Maureen, who spends her days finding haute couture outfits for her German supermodel boss Kyra (Nora von Waldstätten). “The job she does, it’s all about surface and it’s not for her,” says Assayas. “She despises it, she’s angry, she’s frustrated.”

Yet Personal Shopper is no lampooning of the fashion industry; Assayas uses it as a backdrop to create a character study of a woman questioning her own identity, femininity and spirituality. With Maureen also a medium, and mourning the loss of her brother, her desperate need to commune with her late sibling leads to an increasingly edgy and eerie set of circumstances. What emerges is a portrait of psychological breakdown akin to Roman Polanski’s Repulsion.

Assayas has recently completed work on the screenplay 'Based On A True Story' for Roman Polanski to direct, starring Eva Green and Polanski’s own wife Emmanuelle Seigner (Carole Bethuel ) (Carole Bethuel)

“When I started imagining the character of Maureen, she is like all of us,” says Assayas. “When you lose someone who is dear to you, who is part of you, you live in this kind of limbo where you have not accepted the absence. You have not accepted the fact that the person is not here. We’ve all been through it in one way or another; you can call it ghosts, you can believe more or less. I believe less but I do believe. I believe in the milder, extremely modest version of communicating with the other world.”

Has he ever seen a ghost? “No, I have not seen ghosts, but I have been living with ghosts,” he replies. “I’ve been having conversations with the departed – my parents are present with me every single day or friends who are close to me. They are still around. They float around. That’s what ghosts are about really.” Don’t expect the Gallic Ghostbusters, however: Assayas was more inspired by 19th Century ‘spirit’ photography which set out to capture spiritual entities on film.

Born in Paris, living in what he calls “a fairly middle-class environment”, Assayas’ own background is rooted in cinema. His father was Jacques Rémy, who developed an impressive career in France as a director and screenwriter. Assayas began his own path towards directing by helping his father ghost-write TV episodes when his health was failing towards the end of his life. After graduating from high-school, he came to Britain, managing to score an internship in the editing rooms at Pinewood Studios.

Stewart, who also starred in Assayas' film 'Clouds of Sils Maria', inspired his screenplay 'Personal Shopper'

It was an eye-opening time. “I served tea to Charlton Heston,” he recalls, with a smile. He was also there when Richard Donner’s 1978 film Superman was being made. “I would visit the set once in a while; when they were shooting the explosion of the Planet Krypton, with Marlon Brandon, I was there.“ Writing and directing short films, he began penning scripts for others – notably André Téchiné’s Rendez-vous – before making his feature debut with 1986’s Disorder.

Since then, Assayas has crafted some diverse works, from the Hong Kong cinema-inspired Irma Vep (with his former wife, Maggie Cheung) to the controversial Demonlover to his sublime five-hour epic Carlos, about the Venezuelan terrorist Carlos the Jackal. Shooting Personal Shopper, however, took him back to Paris for the first time in years. “It’s also disturbing for me,” he reveals. “This was [just] before the November 13 attacks, and two weeks later, we would not have been able to shoot those scenes.”

Assayas recently completed work on Based On A True Story for Roman Polanski to direct. An adaptation of Delphine de Vigan’s novel about a writer hounded by an obsessed fan, starring Eva Green and Polanski’s own wife Emmanuelle Seigner, it’s Assayas’ first script for another director since 1998’s Alice and Martin, which he co-wrote with his mentor André Téchiné. Of his time with Polanski, “I think it ended up being a satisfying experience for both of us,” he says.

He’s also trying to resurrect Idol’s Eye, this time with Sylvester Stallone in the lead as mobster Tony Accardo. “My movies have always been shown [in the US] and they’ve always had some kind of audience recognition,” he says. But he’s all too aware that when you enter into Hollywood, you’re forced to play on their terms. “Up to a certain point, you have control on the film and there are always ways to make them. When you go beyond a certain point, you are dependent on things you have no control of.”