The perfect 10s for Branagh's performance in the title role of Ivanov, a Chekhov play adapted by Tom Stoppard, prompted BBC2's Newsnight to ask whether Britain was entering a new golden age of theatre.

Ivanov is the first show in a year-long season that the Donmar Warehouse is bringing to the Wyndham's Theatre, featuring Dame Judi Dench, Sir Derek Jacobi and Jude Law, who will play Hamlet under Branagh's direction. Juliette Binoche and Ralph Fiennes are headlining at the National Theatre, Michael Gambon and David Walliams are about to open in Harold Pinter's No Man's Land, and the Royal Shakespeare Company production of Hamlet, with David Tennant and Patrick Stewart, is such a hot ticket that when London booking opened the box office was taking 2,000 calls every second.

With so much focus on Tennant, backed by his army of Dr Who fans, and other starry names, Branagh's first regular West End role for 19 years generated little initial excitement. Yesterday's man? They're not saying that now. His acting masterclass stunned critics, reminded theatre audiences what they had been missing and set the standard for every other A-list performer this season. And in the most elegant riposte to his doubters, the 47-year-old reaffirmed his talent by playing a debt-ridden fortysomething in the throes of a midlife crisis.

It is tempting to declare Branagh the comeback kid, although admirers of his work on film and TV will know that he never really went away - in the autumn he stars in BBC1's adaptation of Henning Mankell's Wallander. More accurately, Ivanov could herald the moment that Britain's critical establishment learned to love Ken again.

'I'm thrilled we've got a huge event on our hands now with him at the centre of it,' said Michael Grandage, the director of the production, speaking to The Observer from New York. 'What's happened is that Kenneth Branagh is back in a classical stage role, which doesn't come around very often, and he's doing it in the middle of the West End. All the planets are in alignment and I'm glad that it's being celebrated. This week proved that he's never been written off.'

From the day that he published his autobiography at the age of 29, and was hailed as 'the new Olivier' after playing Henry V, Branagh has been a target of tall poppy syndrome - a high achiever who needed to be cut down to size.

He gave the critics plenty of ammunition with films such as Peter's Friends and Frankenstein, easily dismissed as self-indulgent follies. Friends believe that by hyperactively acting, directing, writing, film making and running his own theatre company, all before his 30th birthday, he showed a can-do attitude that offends a nation still in love with understatement and the underdog.

Actor Richard Briers, who has been directed regularly by Branagh over the past 20 years, said: 'It's difficult in England because you put your head above the parapet and get it shot off. He's a loner and he's done a lot on his own. He's a great achiever and often English people don't like that. But I think he's now turned a corner and they've realised that he's a very genuine person.'

Briers, whose daughter Lucy is appearing with Branagh at the Wyndham's, added: 'Lucy says he goes into every dressing room half an hour before the start and asks if they're all right. Everyone admires him because he always has his feet on the ground and he's never starry or stupid. He has greatness in him; I've always felt that. '

Branagh enjoyed the sort of career start that was bound to arouse envy or suspicion. Born in Belfast and raised in Reading, he was only six weeks out of Rada when he made his professional debut in Julian Mitchell's Another Country, winning an award for most promising newcomer of 1982. He joined the RSC and went on to form the Renaissance Theatre Company, earning nominations for best actor and best director for Henry V at the 1990 Oscars.

He seemed unstoppable. He told the Times last week: 'Because of the relative impact of what I was doing, because of that ubiquity, I suppose people thought there must be some sort of plan. What there was was an extraordinary amount of energy. What might be consistent between then and now is being passionate and energised about the things one loves.'

His private life also drew unwelcome attention. He and his wife, the actress Emma Thompson, were felt by some to be insufferably smug and 'occupied a place in the public gaze somewhere between Burton/Taylor and Becks/Posh,' it was noted recently.

Their divorce in the mid-Nineties was cause for schadenfreude, and Branagh's next relationship, with actress Helena Bonham Carter, did not burnish his man-of-the-people credentials with the media (he has since married art director Lindsay Brunnock).

Some pundits now openly repent their early hostility. Mark Kermode, film reviewer for Radio 5 Live and The Observer, said: 'There were an awful lot of critics who took against this almost presumptuous, precocious someone. I was one of them. I admit that I was wrong. I'm a huge Branagh fan.'

Kermode began to appreciate Branagh just as others were turning against him. He added: 'Branagh's had a love-hate relationship with the press throughout his career. People tend to have extreme reactions. I think the reason is that he's not afraid to be bold, look foolish and fail spectacularly - that's the key to Branagh.'

Indeed, Branagh's CV has defied linear categorisation. Hits have followed misses, misses have followed hits, in a zigzagging line that could induce vertigo. He failed to make it as a Hollywood leading man but won an Emmy for his brilliantly chilling portrayal of the Nazi Reinhard Heydrich in Conspiracy. He also earned plaudits as Professor Lockhart in the 2002 Harry Potter film The Chamber of Secrets and as Ernest Shackleton in a film of the explorer's life for Channel 4. His direction of films such as Love's Labour's Lost and Sleuth was less well received, but in the West End his Morecambe and Wise homage The Play What I Wrote was a commercial and critical success.

While the press turns every new assignment into a triumphant comeback or disastrous loss of form, Branagh just keeps on working. Recently he was in Sweden filming BBC1's Wallander, a £6m series of three 90-minute episodes based on the crime novels by Swedish author Henning Mankell, which have sold 25 million copies worldwide. Branagh plays the heavydrinking, world-weary but razor-sharp detective Kurt Wallander, while the role of his long-suffering sidekick, Detective Martinsson, is taken by Tom Hiddleston, a co-star in Ivanov. There are hopes that Wallander, of which Branagh is also an executive producer, could become a Swedish Morse.

Branagh will also be seen in The Boat That Rocked, a film comedy about pirate radio written and directed by Richard Curtis, who said: 'He was the first thing we shot in the film. He rang me the day before and said, "It's the first day and you'll have a million things going on tomorrow so you can completely ignore me, completely lose your temper with me, completely tell me to do things that I'm not supposed to be doing." He's a director himself and he was right, it was a very complicated day. I thought it was deeply charming of him.'

If there is a question mark over his career, it is whether Branagh the director can ever match the sublime body of work fashioned by Branagh the actor. His Hamlet at the Wyndham's, which he has been working on for a year with Law, might deliver an answer, after which there will doubtless be demands for more stage work from him.

Hamlet is the play that defines him more than any other, and which he turned into an uncut, star-studded four-hour film that posterity might yet judge his masterpiece. A decade or so from now, it is surely his destiny to follow Olivier once more by turning his attention to Lear. The best of Branagh is quite possibly yet to come.

Highs and lows · 1988: Plays Hamlet under Derek Jacobi for his own Renaissance Theatre Company in the first of many performances in the role.

· 1989: Described as the new Laurence Olivier after taking lead role in film version of Henry V. Nominated for best actor and director at Oscars.

· 1994: Directs and stars in Frankenstein, playing the title role opposite Robert De Niro. The film grosses $100m but is savaged by critics.