in Philip Haas's new film, Angels and Insects, Patsy Kensit is bleached from head to toe. The London Film Festival programme said she looked like "a lovely creamy butterfly" but, in fact, there is a ghostly quality about her which is quite unnerving. Angels and Insects is a bizarre and beguiling chamber piece, adapted from an AS Byatt novella and pitched at the middle ground between Merchant/Ivory and Peter Greenaway. The film marks something of a breakthrough for Kensit, as in it she manipulates, to authentically sinister effect, the very decorative quality for which she is both most celebrated and most disparaged.

She breezes into her friendly neighbourhood interview rendezvous - a wine bar just off Abbey Road - tiny, power-suited, beautiful and with a mobile phone pressed between ear and shoulder. Cheek kisses are exchanged with the bar's female owner and the music is turned down in Patsy's honour. She "loathes" promotional encounters such as this one, but concedes that "it is easier to sit down and talk about a piece of work I actually like". Presumably, as someone who has - by her own admission - done more than her fair share of "butt-awful" films, it must make a change? "Exactly."

Patsy Kensit talks very quickly, pausing only to prevent her words being lost in the occasional roar of the coffee machine. The odd lost consonant attests to the "very working class background" which she refers to in numerous different contexts before pulling herself up: "I'm going on about that too much aren't I?" Her unexpected and welcome forthrightness extends to every aspect of her public image. "I'm so sick of reading articles about myself that say 'you think Patsy Kensit is like this but actually she is quite intelligent and has a large group of friends' ." Oh well, back to the drawing board.

When Patsy Kensit's mum ("Just the most beautiful, perfect person you'd ever meet") met her dad ("The first man I ever fell in love with"), her mum was working as a PA for Christian Dior and he had a club in London called The Roaring Twenties and some very dodgy friends. "They were a very glamorous couple," she says fondly of her parents. "I see all these pictures of my brother's christening [Reggie Kray was his godfather] and I'm sure it's the antithesis of how villains would be now - don't get me wrong, I'm not condoning anything, but it all looks so kind of smart."

Did a fast and loose upbringing give her high expectations of glamour in later life? "No, because when I was growing up it wasn't glamorous. By the time I was about seven my father had lost all his money - we lived in a semi-detached suburban street in Hounslow and I went to the local convent." Patsy's father went to prison when she was 10, though she didn't find out about this till just after his death, six years later, when family fears that her growing renown would lead to his tabloid exposure proved unhappily justified. Her mother is dead now too, having finally succumbed two years ago to cancer diagnosed when Patsy was a young child.

Having made her big screen debut in The Great Gatsby at the tender age of four - as the daughter of Bruce Dern and Mia Farrow (who, rather spookily, she recently played in a cheesy US TV biopic) - and working consistently thereafter, Kensit must have stood out a bit at school. "The only time it really became a problem," she remembers, "was when I was in a Haircut 100 video, because at that time they were the Take That of the fourth year. I didn't tell anybody, then it was on Top Of The Pops and the next day I went into school and everybody said 'ooh, you bitch'."

Patsy plunged headlong into London highlife at the brash height of the early Eighties. "Looking back," she admits, "it was horrendous. Capital Radio were doing a lunch for London's 'bright young things' - how Sixties is that? So I borrowed this old black Sixties Audrey Hepburn-type dress off my mum, and Gary Kemp and Steve Dagger (then svengali of Gary's group Spandau Ballet, soon to be Patsy's manager) were there, and basically I kind of pulled Gary, which was kind of bizarre because I was just coming up to my fifteenth birthday."

When Gary took Patsy to the Wag Club, her mum picked her up and dropped her off, and her brother went along too to keep an eye on her. "It was really innocent," Kensit affirms, "I never took drugs, I never drank - that all kind of happened later." What price chemical distractions for a teenager working with the RSC, starring with Ben Kingsley in the BBC's Silas Marner, and winning an obscenely lucrative recording contract, all in the space of a year. (Going to film premieres in Europe, where pop music is a second language, Patsy still sometimes gets asked when her group Eighth Wonder will make another record; her response is "never".)

That's not to mention Absolute Beginners, the golden egg which hatched into an albatross. "It's tough still to be answering 11 years later for work you did as a 16-year-old," Patsy laments. "Anyone - Wynona Ryder, Julia Roberts, Harvey Keitel, Donald Sutherland; I'm not equating myself with these people, but they've all done bad films as well as good films ... that's a career, which is all I'm trying to have".

A year and a half ago, Patsy got a new agent. "She sat me down and asked me what I really wanted, and I said 'I want to be in films that I would go and see'." A solemn oath was sworn to hold off the lucrative straight- to-video cheesecake roles in the hope of something better. Something better duly turned up, first in the shape of Angels and Insects and then (and this Patsy is really excited about) Allison Anders's forthcoming US music industry saga, Grace Of My Heart.

Co-starring in a Martin Scorsese production with John Turturro, Matt Dillon, Eric Stoltz, Ileanna Douglas and Bridget Fonda is something she is understandably quite pleased about. So pleased that, like the rest of her ensemble cast-mates, she did the film for "scale". What does that mean exactly? "It's a pittance - $800 a week or something. Coming from earning - I won't be crude, but a lot of money on B-films or maybe even C-films, and having a heavy heart going to work every day, I was the happiest I've ever been... working alongside someone like John Turturro you can't help but get better."

Self-effacement is Patsy Kensit's trump card at the moment. She's just finished filming for the next series of French and Saunders in the Jane Asher celebrity humiliation role - "They're doing take offs of all these big movies and I'm the love interest every week." An impressive showing as a guest manager in the last series of Fantasy Football League was, she insists wryly, "another huge step forward in my career".

Having topped the league all season, Kensit was pipped at the post by the sad, anoracked form of Fever Pitch author Nick Hornby. "He's a bastard actually," Patsy asserts with unexpected vehemence. "He wrote a terrible thing about my husband [Simple Minds singer Jim Kerr] in his new book. I hope I bump into him again, because if I do, I'm going to headbutt him." Putting this threat into action might be the best way for Patsy to win back the anti-New Lad constituency alienated by her footballing reminiscences.

"I went to see Man Utd play Chelsea ," she enthuses, "Ryan Giggs is a good friend of mine and he plays for - well, you know who he plays for - and I was practically mobbed. I thought 'Fuck me, this is my fanbase, and they're not going to be going to see Angels and Insects!' " Isn't it a bit daunting to be in the midst of a large crowd of football supporters who've all seen you grappling with Mel Gibson in Lethal Weapon II? "No, because I've got a sense of humour about it. Though as we were leaving, my friend did hear some guy shouting 'Patsy! Patsy! Top pussy!', which she thought was hilarious but I thought was horrible," she smiles, somewhat uneasily, "even if it was meant to be a compliment."

8 Angels and Insects is out on Friday.