Dirk Bogarde was not a man who let you know him easily. Over 30 years' acquaintance with him, I found myself slipping farther from anything but polite familiarity.

Once we had been quite close. Long before he revealed it in his memoirs, he told me the incident that had shaped his way of life. He was aged about seven when a pet tortoise that had gone missing one summer turned up trapped inside a hole in the meadow: at least, its shell turned up. Ants had eaten out the soft meat of its unprotected belly. The lesson it taught the impressionable child was: don't ever expose yourself. Don't stick you head out of your carapace. Don't let the world see your innards: if you do, it will eat you alive.

Dirk Van Den Bogaerde, of Dutch origin, son of a newspaper art editor from whom he inherited a more than passable sketching talent, was raised in the still lush swathes of the Thames valley that Kenneth Grahame immortalised in The Wind in the Willows. But he remained all his life a transplanted Continental. He became an English gentleman and film star, but tended to look down on the latter achievement lest it diminish the status of the former. Self-control was needed not to surrender to the vulgar fan worship as the Rank Organisation's pinup boy in the Doctor in the House comedies.

Bogarde's ingenuous young intern Simon Sparrow - though, at 33 passing for 20, perhaps not quite so young - had mothers and their daughters all over England falling in love with him. And why not? He was sensitive, yet manly looking; he had spaniel eyes, but one eyebrow that could be cranked up a notch to assume quizzical amusement at himself; and a slightly lop-sided smile saved - just saved - his face from resembling those generally found on knitting patterns for men's sweaters. A less intelligent chap would have been content with local stardom.

Not Bogarde. He found it all profoundly unfulfilling. Noel Coward had told him, after his overnight success in a West-End play, Power Without Glory, "Never go into the movies - never compromise." He did both, and spent half his life resenting compromises that brought him easy stardom in films he often rubbished later on. His beginnings, though, were more ambiguous and interesting than his Simon Sparrow heyday.

He was the gun-toting, working-class spiv who shot Britain's best-loved bobby, PC George Dixon of Dock Green, in the social thriller The Blue Lamp. On this punk, Bogarde conferred a sleazy glamour, even a sexiness rare in British films then, using his gun like a phallic object to tease and terrify his girl-friend. Had he been French, this streak of eroticism would surely have taken him to the top. But the strait-laced Rank Organisation soon snuffed it out and the county aristocracy, among whom Bogarde established himself in Buckinghamshire or Sussex, soon forgot that their neighbour had ever been a screen tearaway. He preferred it that way.

Publicity at this time pictured him in jodhpurs, in the saddle, frolicking with a mastiff, propping up his Bentley, the template of virile bachelorhood.

The absence of an off-screen girl in his arms, or even in the background, was a worry; but the studio hand-outs made up for it: "For his study," read one, "he has chosen man-sized armchairs." So that was all right.

This was a more innocent - well, ignorant - age. Bogarde was homosexual in a low-key way that surfaced only in his later career and was seldom evident, even to close friends. He had discovered his nature early in life when he was picked up in a fleapit cinema by a man who claimed to know exactly how mummies were bandaged. Taking Dirk home with him, the stranger demonstrated the arcane skills of the Ancient Egyptians on the nude and excited boy. Such misadventures in bondage later assumed more socially acceptable shape in the formal life he led on the secluded country estates he bought and sold, one after the other, thus avoiding the swingeing tax then levied on all other capital gains.

His acting career with Rank fell into three modes, all of which he denigrated. There was Dirk the hero in movies like Campbell's Kingdom, A Tale of Two Cities or Ill Met by Moonlight; Dirk the romantic but low-powered lover, registering selfless sincerity in vehicles like The Wind Cannot Read without giving in to any lustful stirrings of breeze or body; and Dirk the comedy "juvenile" in the Doctor series where the prescription was bedside charm, not to be confused with the bedpan impertinence of, say, the Carry On team.

BUT playing pop-up heroes, cardboard lovers and comic cut-outs quickly palled. A bid to launch a Hollywood career by playing Franz Liszt in Song Without End was virtually without a beginning. Since his Rank contract was expiring, he boldly broke the mould of bland leading men and played a homosexual barrister in Victim. At a stroke, his fan following dropped away like barnacles released from a shapely hull.

This was England before the Homosexual Enlightenment. Forget that much of the country imagined the reference to his character being "queer" meant simply that he was feeling poorly. From being a Middle England pin-up, Bogarde became a pioneer iconoclast - and loved it. Though he himself never "came out", he embarked on a series of roles based, more or less, on sexual outsiders.

A meeting with the director Joseph Losey gave momentum to this liberation. Losey was an outsider, too, a political refugee from Senator McCarthy's Communist witch-hunts in Fifties America. Losey was fascinated by England's class system and the hypocrisies it created. Bogarde proved a subtle exponent of them in Losey's 1963 movie, The Servant, which was also Harold Pinter's first script.

He played a lower-class gentleman's gentleman who corrupts and debauches his gentleman (played by James Fox). The film coincided with the Profumo scandals and thus caught the current of anti-Establishment cynicism that was invigorating arts and entertainment.

Losey was a martinet and a bit of a sadist. Bogarde, like many an actor, was a masochist who reacted positively to artistic punishment. They were made for each other. But no one was closer to him than Tony Forwood, the straight man in Dirk's life, in every sense, who became his manager and live-in companion for the rest of his life. Films like King and Country, Accident, Modesty Blaise and Darling brought Bogarde praise, prizes and the satisfaction of being taken seriously. What they didn't bring was enough to pay for Dirk's and Tony's shared lifestyle. And the rise of working-class stars like Finney, Courtenay, Caine and Bates, all younger than Bogarde, too, made work harder to come by.

He was doing commercials for sunglasses in Italy - with the proviso that they would never be seen on TV in Britain - when he fell under the imperious magnetism of Luchino Visconti and, I suspect, this Italian aristocrat's arch-snobbery as well. Visconti told him his gift was for playing weak men. Bogarde took it as a compliment: better domination by Visconti than indifference in England. What he didn't reckon on was the Italian director's own weakness for other handsome male actors.

The Damned, a chronicle of a Nazi family much like the Krupps, was supposed to be Bogarde's star vehicle. But he found his part cut to the bone in order to accommodate Visconti's even newer discovery, Helmut Berger. For this cruel reversal of fortune, however, their next film together, Death in Venice, proved formidable compensation. As the artist whose waning self-esteem is momentarily revived by a platonic affair with a beautiful young boy he meets on the Venice Lido, Bogarde gave his greatest performance, suggesting a world of physical desire and moral trepidation. The fact that in the film such desires remain unconsummated suited Bogarde's style: he, too, lived a life devoted to discreetly hanging back.

With Tony Forwood, he had settled in France on the hills behind Cannes, taking care to avoid the vulgar film festival except the year when he presided over the jury and, to the fury of the organisers, was influential in denying John Huston a prize. Huston, he was reminded, had come all the way from Mexico. "You do not get an award for f***ing travelling," Bogarde replied.

Bogarde had a good war record, attaining officer rank in the Far East, where a horrifying road accident in which he blamed himself for the deaths his vehicle caused made him swear off driving for the rest of his life. Consequently, Forwood chauffeured him everywhere. But the world they had made together in the Alpes Maritimes, a Little England amid the olive trees, imploded when Forwood contracted a fatal illness and became the patient, not the protector.

A new-found talent for writing proved Bogarde's salvation.

Volumes of discreet autobiography, then novels with a streak of non-inflammatory kinkiness made him a successful author and gave him the means to nurse his companion and, after Forwood's death, resettle himself in somewhat lonely comfort back in London, "a short walk from Harrods", as he entitled a volume of his memoirs: snobbery dies hard. People didn't rush with invitations, for he had put some tart and unwise words into print about the stuffy dinner manners of the English. But honours arrived instead: a D.Lit here, a KBE there ...

I think I may have nudged the knighthood his way. I was a guest at the Prime Minister's dinner table and remarked to Mrs Major that Dirk was in a bad way after a stroke. Norma Major, who was wondering what had become of him, immediately said something to her husband about the pleasure Dirk had brought both of them in his Doctor comedies. I said it was he who now needed cheering up. A few months later, Sir Dirk Bogarde appeared in the 1992 Honours List.

"You haven't cracked me yet," Bogarde once snapped in an interview with Russell Harty. And in a later TV film, he burned his diaries publicly, as if defying the feared biographers to do the "cracking." He gained his well-earned lustre as a much-loved star from a careful judgment of how much light he was prepared to throw on his own nature. He overcame a matinee-idol career that would have satisfied lesser talents. He made himself into a good, sometimes inspired actor. He found a new gift and a more discriminating audience as a writer. And though he died without many intimates around him, an exponent of euthanasia, the virtues of which are best suited to a solitary life like his own, he remained faithful to the most valuable lesson an actor can be taught - leave something to be guessed at.