The new first lady of Hollywood

Yes, she's starry and a little camp. Yes, her Golden Globe thank-yous were painful. But Kate Winslet dominates the cinema as Meryl Streep did in the 80s - and deservedly so. She is the finest performer of her generation, says David Thomson, falling at her size 11 feet

Kate Winslet at the world premiere of Revolutionary Road in Los Angeles. Photograph: Graham Whitby Boot/Allstar/Sportsphoto

My wife and I went back to take a second look at The Reader, not because of the controversy in the Guardian, but because of the feet. I'm not going to spoil the story of the film for you, but near the end of The Reader there is a large close-up of two bare feet. These are supposed to be the feet of Hanna Schmitz, a German woman of humble origins and a hard life, late in her 60s by now. The feet are less than lovely - mottled, calloused, the toenails out of shape, everything well-worn. My wife opined, "They can't be Kate Winslet's feet - must be a stand-in, a foot-in. Perhaps they are Sam Mendes's feet, and he did the shot so she could have a lie-in."

Not to disparage the consideration and fondness between Mendes and Winslet, husband and wife, director and actor, I preferred to think that Winslet is too much the perfectionist to let false feet into her picture. "She'd have been up at four in the morning," I said, "getting the make-up people to give her the opposite of a pedicure." The argument is not settled yet, but researching on the Internet Movie Database website I did find this: that pretty Kate Winslet has very large - size 11 - feet. I rest my case, and I assume that Winslet would take any trouble, from the tips of her broken toes to the proper split ends in her elderly German hair. "Would Meryl Streep entertain anyone else's feet?" I asked my wife. She agreed not. And that is the standard here: Kate Winslet is the heir to Meryl Streep.

If that sounds inflated or premature, consider this: Winslet will be 34 on 5 October, and I suspect that by then she will have won her first Oscar (for The Reader) on the strength of six Academy Awards nominations. Streep won her first Oscar, for Kramer vs. Kramer, when she was 30, and she did not get her sixth nomination until Out of Africa when she was 37. Of course, Streep is still in contention this year, for Doubt, with her 15th nomination. Yet Winslet seems poised to dominate the next few years as Streep did the 1980s. The clearest sign of that was at the recent Golden Globes when she took the supporting actress prize for The Reader as well as the lead award for Revolutionary Road (directed by Mendes). Those two films are grim enough to have won only limited audiences, but no one seems to doubt that Winslet is the actor of the moment.

Of course, Hanna Schmitz in The Reader is never a supporting role. Taken from the Bernhard Schlink novel, and adapted with great skill by David Hare, The Reader is held together by Schmitz - and that may account for the very mixed feelings that surround the movie. In this paper, Peter Bradshaw didn't like it, and in the New York Times, Manohla Dargis wrote a disdainful review that charged the film with too much taste for its own good on the way to a sentimental exploitation of the Holocaust.

I don't share that view; I think The Reader is easily the best and most disturbing film of the year. But again, I don't want to say too much about its story since many people have yet to see the film. So let me confine my remarks to a commentary on Winslet. She plays three stages in Schmitz's life: in the 1930s when she is a tough, lonely woman who has an affair with a teenage boy; then a few years later as the same woman charged as a guard at Auschwitz with monstrous crimes against Jews; and finally as an isolated, ageing woman teaching herself to read.

The most remarkable thing in the performance is not the detail of the look. It's the implacable inner severity of the woman and her lack of self-pity, pleas for forgiveness or any hint of redemption in the way her flawed life also leads her to moments of great happiness with the boy and her triumph over illiteracy. What troubles some viewers, I suspect, is the suggestion that a concentration camp guard can also lead an ordinary, decent life. But isn't that the real menace of evil - that otherwise normal and generous people can act like monsters and savages? When the Nazi war criminal Adolf Eichmann was caught, remember, it was because the man hiding in South America bought flowers for his wife on what the Israeli agents knew was the anniversary of his marriage to Frau Eichmann.

What Winslet has managed is to persuade us is that the lonely woman awoken to life by a boy and the stupid, authority-fearing camp guard are the same person. The real thrust of the film is in asking, "What would you have done?", and only the people who have lived with that question deserve an answer or any semblance of virtue. The way Schmitz calls her young lover "kid" is tender and brusque at the same time, and it is the hook into the ambiguity of the character. It deserves an Oscar.

At the Golden Globes awards banquet, Winslet sat between Mendes and Leonardo DiCaprio, her co-star in Revolutionary Road and in Titanic, 12 years ago, the film that did so much to bring them to attention. Winslet spoke very fondly of DiCaprio at the awards dinner, but it was hard to avoid the different journeys they have taken. Winslet has grown up. She has two children from two marriages. She has taken on a great range of parts. She has moved from London to New York. She has become starry and a little camp (she was a garrulous thank-you artist at the Globes), but she seems to possess a kind of experience that has not yet descended on the boy-man DiCaprio. That, I think, is the vital point of comparison with Streep. That great actor's prowess has never been a matter of extraordinary technique (as some claim). It is a question of life experience, of being alert to what a film is about. I am not a great admirer of Revolutionary Road - the story of a marriage and a failing dream - but again Winslet lets the film mean much more than DiCaprio's eyes seem to comprehend.

She was "Rose" in Titanic, if you remember, and at that time it was easy to think of her as an old-fashioned English rose. Her name, her voluptuous figure and her look suggested the 19th century more than the millennium. Born in Reading, she suggested the home counties and a nicely brought-up girl. Her early record was as a pretty character in the English costume classics. Emma Thompson cast her to be Marianne Dashwood in Ang Lee's Sense and Sensibility. She was the life force as Sue Bridehead in Michael Winterbottom's Jude. And Kenneth Branagh chose her to be Ophelia in his Hamlet. But even then, a few people remembered the danger in her soul, as well as the mad romance in her eyes, when she played one of the young killers in Peter Jackson's Heavenly Creatures (made when she was 18 and still one of her great performances). There was a "nice" girl who was also a killer, and the crossover was as smooth as silk.

During the decade or so between Titanic and now, Winslet demonstrated her independence, her courage and her willingness to make some mistakes. Her films were a mixed bag: she was the hippie mother in north Africa in Gillies MacKinnon's Hideous Kinky; she was in Holy Smoke; she was more beautiful than ever and more ready for risk as the servant girl in Philip Kaufman's Quills; she was far too routine in wartime espionage thriller Enigma; she was radiant as the young Iris Murdoch in Richard Eyre's Iris; she was with Johnny Depp without really catching fire in Finding Neverland; she was a game trouper in John Turturro's Romance & Cigarettes; she was outstanding in Todd Field's Little Children; but wasting away in the ponderous and heavily arty remake of All the King's Men, and in The Holiday where she and Cameron Diaz swapped homes.

Her choices in that era show a free spirit, and Winslet is the child of English actors who were lucky to keep in work and ready to try anything. Her marriage to Sam Mendes (made in 2003), may have changed her. Mendes is smart, very likeable and very ambitious. A top director in London's theatre, he crossed over to movies and won the Best Picture and Best Director Oscars with American Beauty. He is bound to be a very helpful adviser in Winslet's career, and he may have been the driving force behind their move to America - he has big plans for theatrical partnerships between London and New York.

The Oscar will make Winslet one of those actors likely to see the best scripts early - but she has serious rivals in Cate Blanchett and even Nicole Kidman (who was actually the first casting for The Reader). It's tough to imagine Kidman blooming in the very harsh air that Winslet breathes as Hanna Schmitz. Kidman likes to be liked and she wants to be pretty. Still, the more clearly Winslet becomes a lead actor in big American pictures, the more likely she is to face the test between being liked and being good and dangerous.

There's little doubt about where her best instincts lie - never forget her performance in Michel Gondry's Eternal Sunshine of the Spotless Mind. But it is possible that she will find that kind of work more easily in Europe. Revolutionary Road proved she can play American - she is not too far behind Streep in her command of other voices. How long will it be before she and Mendes work together in the theatre? And how long before some smart director listens to her talk in public and deduces that she has a natural talent for comedy? To be a serious actor these days can mean wallowing in tragedy - and Winslet got some criticism for saying in advance that doing a film about the Holocaust might bring her an Oscar. So why not a film about a woman with that wry sense of humour and the guts to speak out, even if she is mocking herself? I'm sure that Winslet can do Streep and most of the things Cate Blanchett can do, but can she do comedy in the manner of Carole Lombard, Barbara Stanwyck or Katharine Hepburn? Why doesn't Mendes try a remake of The Philadelphia Story or The Lady Eve? After all, in the hard times of the 1930s and the war years, American movie theatres rocked with laughter and women had a lot of the funny lines. What about a picture with a beautiful woman who has size 11 feet?