Valerie Solanas, the 'I' in the film's title, was a fiery, dynamic, vital and unusual woman who was a brilliant feminist and radical thinker who was not so much misunderstood as dismissed by her generation.

At a photo exhibition of images of the late sixties, I saw a shocking photo of a man's torso, his head obscured, as he held up his shirt to reveal the twisted scars that criss-crossed his belly. It turned out to be a photo of Warhol after the savage operation that removed several slugs from his body. For a long time I thought Valerie Solanas was a crazy who had targeted Warhol for a knife attack. Such distorted impressions were righted in viewing writer/director Mary Harron's outstanding film I Shot Andy Warhol. With her meticulous research and expert casting, Harron has made a stunning film that beautifully transports us to the heady days of the New York pop scene during the late sixties and, more significantly, how it was viewed by a young, free-thinking, anti-social fringe dweller.

As Valerie Solanas, Lili Taylor gives the finest performance of her career, which is already brimming with vivid performances in films such as Mystic Pizza, Dogfight, Pret-A-Porter, Abel Ferrara's The Addiction and Allison Anders' potent portion of Four Rooms.

It wasn't easy for Taylor to get under the skin of such a vital, interesting and dynamic character.

Nevertheless, Mary Harron, had completed seven years of research and built a complex portrayal from a range of sources, such as transcripts from the trial, psychological reports, comments from neighbours, enemies, allies as well as Solanas' writing, especially the infamous S.C.U.M. manifesto. Solanas was the founding and sole member of S.C.U.M - the Society for Cutting Up Men. Taylor admits the manifesto afforded her the greatest insight. "I realised all these selves were apparent throughout the manifesto. She was so unconscious. She didn't realise how transparent she was. But still a very complicated person and very hard to understand. First she just didn't seem real to me. I couldn't imagine her in real situations. That was the first thing I had to do. All these assumptions that I had - she disproved them all. I thought she would be very mean with men - very aggressive. She's very shy and nice. So, every day I was surprised."

The film establishes a parallel with Solanas and Andy Warhol, yet he is more of a character who kept his distance. Taylor says she thinks Solanas had a deep attraction to him, that he was carrying something for her, almost like holding up a projection. His asexuality, androgyny, his coolness, his reserve - these were things he had down, so well and she wanted them so much. Also she wanted to make an impact upon him and that was his point of power. What the film clearly illustrates is how passive Warhol was, but how he chose who was going to have an impact on him. Adds Taylor, "Somebody said, 'Everybody wanted to shoot Andy - she was the only one who did it.' I think she also was in love with him in a very twisted way. I don't think she understood her actions when she shot him."

Once you see Taylor's performance of Valerie Solanas, I'm sure we will all have a better understanding of who Solanas was. Yet it's difficult to understand her mounting paranoia, which I don't think is lunatic behaviour but stops short of it.

Taylor explains, "It's almost mysterious. Is it just the way the days are going, or the stars are constellated? All that - and all of a sudden the chemicals start revving up and the IQ's too high and she's just going going going -- and something just snaps and BOOM! Why do some people snap and some people don't? Why couldn't she make it? Why? She had so much potential and yet she was such a nihilist. She sabotaged her life. And they were misdiagnosing women then so it's hard to know, what she was, really."

Mary Harron says you could read the manifesto as a satire if she hadn't actually gone and done it. Taylor agrees emphatically. "Absolutely. The manifesto is very funny. Valerie said in an interview - They said 'Do you really want to kill all men?' and she said, 'Course not. What do you think, I'm crazy?' She knew what she was doing, in certain ways, and in other ways she didn't. But she was very funny. I saw the humour in the manifesto when I read it. She was started talking about her plan of killing all the men, I just thought it was so outrageous that it couldn't really be her plan of action.

"When I read that manifesto I'd never seen anything like it, and even today I still don't read writing like that; that's so unapologetic, that just crushes though all these layers we have and gets right to the crux. If we had fifteen women in a room she'd be perfect for one part, to shake things up, getting us riled up and then get Valerie out and pull somebody else in who is a little bit more diplomatic. I don't even know if she wanted to stir things up, I don't think she knew any other way."

It's clear Taylor really likes Solanas. "I do, I empathise with her. I wouldn't want to be her friend, though. She was very anti-social, she was the only member of her organisation. She wasn't really into getting along. She was very irascible, controlling, driven -- and she didn't listen that well."

Solanas has a lonely energy in a world of cool. During most of the movie she has her sense of humour but then she lost it and suddenly she was without that element that was what was helping her to survive. Her sexuality was a driving force of the writing and the whole act, yet she tried to kill her sexuality. She wanted to eviscerate any part of it, and that's why she was attracted to Warhol. Here was a lesbian who had never been in a relationship with a woman, in other words she had a dream but didn't live it. Also for Solanas to be a feminist and to be selling her body would have been an almost intolerable thing to live with. Perhaps she felt her sexuality as a woman was a negative force that was going to limit her.

Do you feel that Valerie Solanas was a misunderstood person - does the film set it straight?

"I don't know if she was misunderstood. I feel she was dismissed and shoved into the way back and I feel she was complicated and had a lot of faults but to dismiss her completely isn't right. I know I learned certain things from her. So at least people can read the manifesto and see this very complicated woman who lived. It's yet one more woman to add to this narrow spectrum that we have of women in film and theatre."