His style has not always been to everyone's taste - the critic Benedict Nightingale once wrote that "He is an actor very prone to trills and cadenzas" - but Ian McKellen is now considered, without doubt, to be our finest classical actor. He had put a marker down on this title as early as 1974, in his debut season at the Royal Shakespeare Company, when his chilling interpretation of Macbeth prompted Michael Billington to remark, "If this is not great acting, I don't know what is."
The prizes and plaudits have come thick and fast ever since. He has won five Olivier Awards and even a Tony for his Salieri, in Peter Shaffer's Amadeus, on Broadway in 1981.
Britain had found its Great Classical Actor. But it was only after joining the National Theatre in 1984 that he finally removed any lingering suspicion that he was just a serious actor over-reliant on a sonorous voice. As Platonov in Wild Honey, he delivered a towering comic performance - one minute a dejected slump of self-pity, the next, a leaping, hungry enthusiast.
He has excelled playing professional soldiers, and there are plenty of them in Shakespeare, for whom he exhibits an immense intellectual and emotional passion. His was a bold and bloodied Coriolanus, his Iago for Trevor Nunn had a riveting intensity, while his humpless, half-paralysed Richard III in 1990 produced some of the best notices of a glowing career. Clare Higgins, who played opposite him as Elizabeth and is no slouch in the acting department herself, describes that year as "the best learning experience of my life. Within its context his performance can turn on a sixpence. He inspires you and makes you feel rather bigger and better than you are. You come away feeling like that advertisement for Ready Brek."
His Richard III won him his fifth Olivier award. You might expect McKellen to be a little blase about the shelfloads of awards he's picked up, but in fact, for him, they're a tiresome irrelevance. While he has earned his place in the hall of fame as "Ian McKellen: The Great Classical Actor", it may not be how he will be best remembered. Nor does he want to be. For his lasting claim to fame may well be as "Ian McKellen: The Great Classical Actor Who Came Out".
McKellen now says that he despises the man who remained closeted for the first 49 years of his life. As his early brush with the sensibilities of poor old Councillor Kidd suggests, McKellen never shied away from parts that could cast doubt upon his own sexual preferences.
In a West End now awash with gay plays, it is hard to imagine how shocking it seemed, and how much opposition it provoked, when, in 1979, McKellen agreed to play the part of Max in Bent, Martin Sherman's play about the the persecution of homosexuals in Nazi Germany. It was largely McKellen's involvement that persuaded a reluctant Royal Court to mount the play.
In a profession which has always maintained a self-regulated code of silence about its gay brotherhood - and where, even today, the coming- out of Nigel Hawthorne elicits headlines of the "Oh Sir Humphrey" kind, McKellen's conduct of more than 15 years ago is, at the very least, understandable. But that he chose not to reveal his own sexuality at that time still disappoints him.
Martin Sherman feels that McKellen is being too hard on himself.
"He left the RSC in 1977 to do it. Back then it was an act of extreme courage. We never discussed coming out, but he didn't deny anything. He didn't have phoney girlfriends and he was always seen in public with his boyfriend. He was not so far in the closet as he now thinks. He was braver than most of his peers."
McKellen stayed in the closet for a further 11 years. While it was the notorious anti-gay Section 28 that finally persuaded him to take the final step, it was the combination of a rare flop and a chance meeting that paved the way for his alternative career as a gay activist. British audiences loved Wild Honey, but when it transferred to Broadway in 1986, the critics didn't. The show closed and McKellen embarked instead upon a tour of the US with his one-man show, Acting Shakespeare.
He spent a month in San Francisco with Armistead Maupin, the author of Tales of the City, and was treated to a subtle crash course in gay politics. Upon returning home, he performed the show for three months for no money for the Aids Centre, the London Lighthouse. He raised half a million pounds. And came out.
On this hot summer's afternoon Sir Ian McKellen sits sprawled across a wooden chair in his Limehouse home, looking out over the Thames, sipping a can of Diet Coke through a straw.
He has a couple of hours free between costume fittings, discussions with a publicist, meetings with his assistant and preparation for the next day's work, yet he seems almost ludicrously at ease. It is seven years since he revealed to Peregrine Worsthorne on Radio 3 that he was gay, but he still has the look of a man newly unburdened. At 56, he exudes a sense of freedom and youth; he is truly a changed man. And, it is said, a changed actor.
"Acting is to do with self-confidence. I gained mine through being an actor, finding a place to which I could escape and feel fulfilled. There are now few people in whose company I feel at a disadvantage, but I used to feel that a great deal because I wanted to tell the world that I was gay. Self-confidence means that you can take a few risks and I've always felt that my acting was about that, daring to make a fool of myself."
He pauses, deep in thought. "Playing Uncle Vanya, I allowed myself to try and display his heart in a way I couldn't have done before. Not that it was my heart, but it felt to me like a bit of an advance."
Coming-out has released a boundless energy in all areas of his life. He was one of the founder members of Stonewall, the lesbian and gay lobbying group, and is seen by many as a figurehead of the lesbian and gay movement. He is less than happy at this perception. He describes his role as being a fund-raiser and an "awareness raiser".
"I don't feel I'm crucial to Stonewall. I don't have the expertise that someone like Angela Mason, the executive director, has. As for its success in changing the law, you'd have to say it's going very slowly but that is scarcely Stonewall's fault. We have a government that isn't very interested."
He used to define himself solely in terms of his work. "Now I see myself much more in terms of other people. I've become very picky. Theatre takes an awful lot out of you. At least the way I do it. It's much easier to skip off and do a movie and then have time for everything else in my life. So am I going to run the National Theatre? Of course not." I didn't even ask the question.
Consult his itinerary for the last year, and you get the impression that McKellen feels empowered to do anything he chooses. He has been fund-raising for lesbian and gay causes across the country; playing sell-out performances on Broadway of his autobiographical one-man show A Knight Out; forging links between the National Theatre and the Market Theatre Johannesburg; and, most significantly, developing an entirely new career. Last week, filming began on Richard III. In addition to playing the title role, he is executive producer and has written the screenplay. It's all very Hollywood.
"It means I am allowed to interfere whenever I want," he laughs. The film is based on Richard Eyre's National Theatre production. "We were doing a very available version of the play. Its Thirties setting clarified the hierarchy and the society in which Richard flourishes. It allowed the audience to be led into the politics of the play, which isn't always true of productions in so-called authentic costume."
He kept badgering Richard Eyre to film it. Finally, Eyre pointed out that there was no screenplay. "It really hadn't occurred to me. I can't emphasise enough the depths of my ignorance."
At that point, his film appearances had been rare, although in 1969 he played opposite Sandy Dennis in the almost forgotten A Touch of Love, which was based on a novel by Margaret Drabble with whom McKellen had acted at Cambridge ("I can't believe how camp I was," he remarked after a recent TV screening). As for his performance as the notorious heterosexual, Jack Profumo, in Scandal, the first role he took after publicly coming out in 1988, he wouldn't watch it. "That hairstyle made me the laughing stock of five continents." Undeterred, he began writing.
The final screenplay, co-written with the director Richard Loncraine, is fairly removed from McKellen's first draft. "It was full of things like 'Call up Lord Buckingham' - cut to actor with telephone - 'Lord Buckingham?' The telephone is very tempting, but I now realise it's a bloody nuisance in movies because the actors aren't looking each other in the eye."
Three drafts later, he set off for Hollywood to raise the finance. He also took on as much screen acting as he was offered. He has played everything from a dry white South African in Six Degrees of Separation to a very funny deadpan cameo as the Bergmanesque Symbol Of Death in Schwarzenegger's The Last Action Hero.
Throughout our interview he has been eloquent and effusive. He is not one of those actors who falls apart without a script. Discussion about the casting of Richard III, however, brings out a rare degree of reticence. "Nobody is ever first choice," he observes, stroking his long jaw. "Peter O'Toole wasn't first choice for Lawrence of Arabia, but there's not much point saying it was Albert Finney. At the moment, to talk about it might upset someone's self-confidence. The people who financed the movie were not first choice, nor the producers, nobody was." He pauses, an impish grin spreading across his face - "apart from me".
First choice or no, the signing of Robert Downey Jnr (with whom he appears in the forthcoming film of Rose Tremain's Restoration) and Annette Bening has suited the backers and ensured worldwide distribution. But how will they play alongside the oh-so British Maggie Smith and Nigel Hawthorne?
"It was a very early idea that Queen Elizabeth and her brother should be played American. She is a very independent sort of woman. Her family are outside the main power structure and are looked down upon. Everyone really regrets that Edward IV married this dreadful widow. Set it in the 1930s and it doesn't really ring true that he should have married someone out of his class. Unless that person is foreign. And of course we very nearly had an American Queen, Wallis Simpson."
He is enjoying playing with his new box of tricks now that shooting is underway. Searching for a Thirties parallel for the small but pivotal role of Lord Stanley, McKellen decided to turn him into an Air Vice Marshal who joins Richmond's forces, taking the RAF with him.
"You hear a whirring sound building up and then we look up to see the bombers arrive. When Edward Hardwicke turned up on day one in his blue uniform, he looked so exactly like an Air Vice Marshal I almost cried with happiness. I'd had that idea, and here it was in front of my eyes, courtesy of Angel's, the costumiers, and his perfect RAF moustache, which he happened to have. That's when I understood the thrill of writing a screenplay." McKellen is playing Richard as a fascist leader, but his pleasure in the process is more benign.
The film will be released in November. What then? Given his nightly improvisations in Napoli Millionaria at the National, why not Ian McKellen doing stand- up comedy? Why not indeed? "If I could go out and do half an hour in front of an audience and make them laugh, I could retire very happy. I spent a day in Blackpool being the feed in Lily Savage's show. What a privilege. And then there's drag. And panto..."
He stops himself, midstream. "Is it all to do with coming out and thinking, 'Oh fuck it, why not?' I don't know. I've got the knighthood. I went to work on A Knight Out, on the Ian McKellen who wanted that sort of respectability. You know, 'Like me, admire me, honour me, give me my worth', because I didn't feel I had any. And I came out and the minute I did, someone said, 'That man deserves a knighthood.' Wasn't that a nice irony?"
He's contemplating the expected memoirs but thinks he'll end up, inevitably, writing about being gay. "Ten years ago, if I'd wanted to define myself, it would have been as Ian McKellen, actor. What else was there? Now it's more like Ian McKellen, a gay man who acts."