Why Susan Sarandon rocks

She looks very uptown New York - petite in an ivory cashmere sweater, floppy grey pants and black slip-ons, chestnut hair tied back. Her tone is matter-of-fact and she has the dry wit of the celebrity sophisticate: "I choose projects I can talk about for days because now you do publicity for as long as it took you to shoot the movie," she says with a smile.

Susan Sarandon is in town to publicise Cradle Will Rock, a film about censorship of the arts in 1930s New York. It is the second film that Sarandon and her partner Tim Robbins have made together with a political message, the first being Dead Man Walking for which she won an Oscar in 1996. "It was certainly a nice build up getting nominated all those years [for Atlantic City, Thelma and Louise, Lorenzo's Oil, The Client] and then finally getting it when your beloved directed it and you're still speaking to each other."

But Robbins and Sarandon are almost as well known for their collaboration at the Oscar ceremony itself. In 1991, co-presenting an award, they protested about a US government detention camp for immigrants. The Academy banned them (though, of course, they were back soon enough) but the incident summed up their role as the self-styled rebels within. "The fun of being an artist is to challenge peoples' perspective. In the Thirties you were putting your life on the line - we have it a little bit easier."

The roles she has played, the fact that she is probably the only non-surgically-assisted, 53-year-old woman in Hollywood, and her reputation for being a bit of a Leftie activist (at least in American terms) have put Sarandon in a different league. Alongside her, other actresses seem insubstantial, mere girls in the presence of a vital woman. At the London Film Festival last November, a number of the questions the audience asked would have been more suitable for Hillary Clinton. Besides the groups of crop-haired women who thanked her for "giving us Louise" (as in Thelma and Louise) and the coy enquiries about what it was like working for Robbins, one man wondered if she'd considered running for President, at which she didn't bat an eyelid but gave a diplomatic, never say never, reply. Is she conscious of being a role model? "Well I can't help but be, because everyone tells me I am. I guess it's a combination of things I've done off screen and on. As a celebrity I have the power to make a difference and, once you are identified as someone who cares, there aren't enough minutes in the day to deal with all the issues."

If, at this point, you are thinking Susan Sarandon should get over herself, then get a load of the Sarandon 50th birthday celebrations. "Tim organised a kind of tribal journey to this island and my girl-friends had been working on this ceremony. We sat around in a circle and they all talked in turn about qualities in me: someone would say: 'I've always been very moved by Susan as a mother', or they focused on the activism, or the intellect. And then we got a bottle and everyone put in notes and we sealed it and everyone got naked and we threw it in the ocean." But there is a point to all this. The classic Sarandon role, both on screen and off, is that of big sister or maternal provider, whether it's befriending a prisoner on death row, or being Julia Roberts's mentor.

"I was the oldest of nine children, so it took me years to learn, where men were concerned, to save mothering for little people. I was raised to make everybody happy, so it makes stopping the show at the Oscars very, very tough." She was also raised a good Catholic girl, which makes the fact of her divorce from Chris Sarandon in her mid thirties, having a daughter (now 14) with an Italian film director, living with Louis Malle, and subsequently raising a family with a man she is not married to, equally tough. "I always had questions even when I was being force fed the whole Catholic institutional line. And then it really hit the fan when I was in college in the late Sixties at a very tumultuous time in America. I just took for granted all this anger that kids today don't get to experience because everyone's on Prozac."

Although she takes her "activism" very seriously, Sarandon's real achievement to date seems to have been raising the glass ceiling for actresses. "Oh, I'm a huge, huge fan of women, and clearly we are the stronger sex, there's no doubt in my mind." She found real success with age, and the turning point came eight years after her first Oscar nomination in 1980. She was 42 when she played the ultra sexy baseball groupie in Bull Durham opposite Tim Robbins (they've been together ever since). Astonishingly, in a career that spans getting on for 50 films, all her best work has been done post 40. "I guess I've pushed the envelope somewhat - I didn't hang up my sexuality when I turned 40. But if you look back, Katharine Hepburn and Bette Davis were not in their twenties when they were doing those parts, it's just that we've got so inundated with youth culture."

Some would say she has compounded the pressures of ageing by living with a man 12 years her junior. "To me he's really ageless, and he's totally grey now, so maybe I've aged him. We live in New York and maybe if I were trying to survive in LA it would be different. But I'd rather work on the inside, on lifting my spirits instead of my face."

She says she's at her best when she's scared. "All different kinds of things scare me. Doing a film like Dead Man Walking, where you know that you look worse when you get on the set than you did when you got out of bed is tough, because I can't say that I'm without vanity. Playing a character that's unsympathetic, like the character in Anywhere But Here, and having to wear those heinous pink leggings, can shatter you. I think nudity is very tough, I always think they should give you stunt pay for taking your clothes off." And then there are movies like Stepmom, and Lorenzo's Oil which touch on emotions close to a mother's heart.

Sarandon suffered from endometriosis as a young woman and was told that she would never have children. Now she has three. "The first one kind of slid by and cured me. I have to say that none of my children was planned, they were just welcome gifts." That's very comforting news, I say. "For the older ovaries? Oh yeah, a lot of women say you have given me hope of having children later in life. I recommend people go to Italy and have a wild affair and eat well, and relax about it. You know, for me, the muscles that you use to act are the muscles that you use to love. It's about being really open and not being neurotic."

?Cradle Will Rock is released this Friday.