She was her own montage: seven husbands, eight marriages, diamonds beyond the counting, scandals like forgotten promises, two Oscars for films that showed the immense creative journey she could take, soaring as if on a single breath from the ridiculous Butterfield 8 (playing a hopelessly old-fashioned Hollywood "whore") to Martha in Edward Albee's and Mike Nichols's Who's Afraid of Virginia Woolf?, a defiant wreck out of the true heartland of American tragedy. She had the range, nerve and instinct that only Bette Davis had had before – and like Davis, Taylor was monster and empress, sweetheart and scold, idiot and wise woman. We went in awe of her, but with one word or a knowing smile she assured us she was one of us. So beautiful, she could go crazy, too – and then move on.

Those two Oscars were only six years apart, and it wasn't so much that they used a different Elizabeth Taylor (for she had always grasped the affinity of trash and class in her art and business). It was rather more that in that interval there had come the folly of Cleopatra, her first near-death in the London Clinic as they tried to film the Egyptian epic in Britain, and then the fateful meeting in Rome with Richard Burton, the Antony she carried into life as if at last the romantic actress had found her real passion.

She was in awe of Burton – his class, his Welshness, his reading, his literary ambition, his ruthless, pessimistic candour, to say nothing of his exceptional instinct and nature as an actor. There were plenty of people, especially in the London theatre, who predicted she would ruin him. And some of them asked, "What did anyone expect?" when Burton died too young and maybe with too few grand credits to his name (as well as no Oscar). But Burton was always in charge of his own demise and ruin, and he recognised that Liz was not just his equal as actor and self-destructive force, but much his superior at surviving. To read Melvyn Bragg's biography of Burton, which quotes extensively from his journals, is to see how passionate and turbulent their love was – to say nothing of their pioneering of the thing we now call celebrity. But Burton ached with respect for her. He had seen the real thing, the last star, and a camera actress who had been born knowing more than he could ever learn.

So she went from childhood, when her violet eyes were one of the touchstones for Technicolor, to being a devoted patron in her later years to those who were sicker than she was. She gave up acting because I think she knew that without her astonishing youthful glamour and sexuality, she was in grave danger of betraying her own past (and her own dreams for herself). After all, to millions she had been the most beautiful woman on screen for a couple of decades, and when she was only 18, in A Place in the Sun, she had entered into one of movie's modest exquisite romantic auras, with her partner in that film, Montgomery Clift.

It's a film based on Dreiser's An American Tragedy, and in the book Taylor's character is the rather empty rich girl who takes the hero away from a first love (Shelley Winters in the movie). But as George Stevens made the film, Winters is a drab, whining figure – someone dreamers almost want to have removed … and murdered. Liz and Monty are the prince and princess in an impossible love story that ends on Death Row. But thwarted love stories are the best, and at 18 Liz could look at Clift, the camera and us, and convey the magic words that inspired classic American cinema – "If only!"

Clift was just one of the adored figures who could not really stay with her. They were so in love on screen that it may have surprised them to notice in life that they were not quite of the same sexual disposition. But Taylor had a great gift for friendship, and she looked after Clift as best she could – she was there when he had his terrible car crash in Los Angeles and did her best to hold his broken head together. She lost the impresario Mike Todd after a brief marriage. She lost screen partners like James Dean and she lost Rock Hudson. There was a turning point, for in Hudson's tragedy she seemed to see a new role, and so she helped raised hundreds of millions of dollars for Aids research and relief. Along that way, so much of her early trashiness was forgiven by the public so that at her death, at last – for hospital was one of her long-running roles or duties – there is much grief and sorrow for her.

Young people now may hardly know her, and it is hard today to conjure up the sexiness, the daring, the insolence of some women on screen in the 50s when the Production Code still prevailed. But to see Taylor filling a slip for the first part of Cat on a Hot Tin Roof (that was 1958) was to lose track of Tennessee Williams and Paul Newman, and to dwell on the sheen, slipperiness and near-graspability of that flimsy notional garment. It may look a silly, over-talkative film now – and there are Taylor pictures where the sheer visual glory has dated comically – until you let the story melt away and just gaze at her: in Ivanhoe, say, or Beau Brummell, or The Sandpiper or The Last Time I Saw Paris. In truth, in those years just before she met Burton, Liz Taylor was doing whatever Metro-Goldwyn-Mayer told her and going nowhere. But in 1955, she was still only 23. She seemed to have been on screen for ever, with Lassie, National Velvet, Mickey Rooney and Roddy McDowall. Then she became the woman of the age.

I daresay the beauty got in her way, and men – nearly all of them unsuitable – lined up to marry her. She had always known she could act, and the more demanding parts and authors never troubled her, so long as they trusted her to hold the screen. But what she deserved was a more modern version of the dream. She had the well of feeling behind those eyes that could deliver anguish and trouble and real difficulties in growing up. That's what A Place in the Sun started, and it is still her authentic masterpiece, the most iconographic thing she ever did. The final telephoto close-ups of her and Clift in their last embrace speak to the entire hope of movie romance.

Don't confuse the issue with Taylor by asking if she was a good actor – or a decent woman. I met her, and I can only say that for a couple of hours she was smart, honest and a great talker – there was no fuss, no coyness, no sham and no act. "What are we going to talk about?" There was Englishness in her, for she was raised in London in the years before the war, and you could always hear it in her voice; more than her eyes or her body, I think, the voice was the key to her screen being: sultry, funny, self-mocking, deadly earnest and intimate – take your pick.

She was a star from 1944 onwards (that was the year of National Velvet). And after the late 80s, she was a figure in magazines and on the internet. She made a great many bad and negligible films – far more than she should have done, granted her ability. But she was raised at a time when young women didn't know how to take charge of their careers. Then her scandal broke out, in the early 60s (remember Eddie and Debbie?), just before the world at large was ready to binge on sex, vulgarity and naughtiness. Newspapers, teachers and churches announced that she was a wanton and worse. She was far better. But it was a moment in history when the world seemed desperate for polite, well-behaved wantons, and Liz did the trick with the grace and kindness of an older sister. "If only!"