Sam Garbarski freely admits that his second feature, Irina Palm, is a cosmopolitan endeavour.

He is a Pole, born in Germany and based in Brussels. His backers come from all over Europe. His initial plan was to shoot the film, which he describes as "a non-politically correct, romantic black comedy", in Belgium. But in the end British producer Christine Alderson of Ipso Facto Films came on board and the story was relocated to London.

Irina Palm features Marianne Faithfull as 59-year-old widow Maggie, trying to raise money to help her sick grandson by working in a Soho sex club. While she unexpectedly excels at her new line of work, matters are complicated when she falls in love with the shop's owner.

"We realised how much better it would be to do it in England," says Garbarski. "Soho is a beautiful micro-world. The whole (English) social context is so much stronger than it would have been in Belgium or in France."

Garbarski did plenty of research in the red-light districts. While he acknowledges that the plot of Irina Palm might sound prurient, he says the film was shot with a great deal of restraint: "We're only showing Marianne's face and her body language. This is the story of a great, great woman who really sacrifices herself for her grandson."

The idea to cast rock legend Faithfull came to Garbarski during a plane journey when he read an article about her appearance in Sofia Coppola's Marie Antoinette.

"It rang a bell. I thought, 'Marianne Faithfull - why not''"

At the time, Faithfull was on a music tour and Garbarski met her in Brussels. "We talked. Marianne is a true artist. Even though she is not a classically trained actress, she is so professional."

Once they started working, Faithfull's iconic status and colourful past were quickly forgotten. "In the film she has nothing of the rock icon. You forget all this. When I told her the way I saw Maggie, she really liked it because it's not her."

Irina Palm's exteriors were shot in Soho and around London, with studio work and interiors filmed in Leipzig and Luxembourg. Garbarski has been heartened by the response of those who have seen the film, which screened in competition at the Berlin Film Festival, and who say it seems like an authentically English project. For this, he compliments his English casting agent, Leo Davis, whom he credits with "really selling the film to good, good actors".

Directing feature films is Garbarski's second life. For many years he ran his own advertising agency, directing his first feature, The Rashevski Tango, in 2003.

He is now preparing a third feature, Quartier Lointain, an adaptation of a Japanese manga.

IRINA PALM

A grandmother goes to work in a Soho sex club to raise money for her sick grandson

Prod cos: Entre Chien et Loup production in co-production with Pallas Films, Samsa Film, Liaison Cinematographique and Ipso Facto Films

International sales: Pyramide

Key cast: Marianne Faithfull, Kevin Bishop, Siobhan Hewlett, Miki Manojlovic.