Enter Nicholas Hytner, stage left (exit Trevor Nunn, retired hurt)

Plenty of well-qualified theatre people turned up their noses at the job of running the National Theatre. Stephen Daldry and Sam Mendes prefer small London theatres and the embrace of Hollywood. Nick Hytner's special qualification is that he wants the part. He always has. "I kept the idea at arm's length, waiting for the time to become right," he says. It became right last Tuesday.

The bright young directors, such as Daldry and Mendes, who have turned their backs on the National condemn it as an unwieldy bureaucracy with an ageing audience that has no taste for new work, and are dismayed at its dependency on the Arts Council. Not Hytner: "It's been like a lodestar for me."

He has retained his enthusiasm despite the mauling Trevor Nunn has had during his term as director, which ends in March 2003. Nunn's welcome to Hytner makes the job sound like an ordeal. For Nunn it has rarely been anything else.

Despite Nunn's record of sustained brilliance as a director at the NT with such productions as The Merchant of Venice, Gorky's Summerfolk and My Fair Lady, his NT is a favourite target both inside the profession (not enough new directors or new plays) and outside (it subsidises the pleasures of an ageing elite).

"There's an element of knock-about in English public life. All you can do is take it on the chin," says Hytner. But he is determined to insulate himself from the criticism that NT directors line their pockets at the expense of the public purse when their shows transfer to the West End or Broadway. Nunn retains only 15 per cent of the earnings he is entitled to from musical transfers such as My Fair Lady. Anonymously, Nunn even financed brilliant ensemble work at the NT out of his own pocket. But he gets no thanks. Hytner has told the NT board that he intends to take not a penny from any commercial transfers: "I don't want the hassle," he says.

Of course, the success of the musical Miss Saigon, which he directed in London and New York, means that he does not need the money. "That's not the point. I want to show I'm on the level." But he will not crave the spotlight. "You won't see me at parties." He rarely illuminates his life, but the bare facts are these: He was born in Manchester on 7 May 1956, the son of a lawyer who became a QC and a mother who had been a publicist for Granada TV. He went to Manchester Grammar School, where he acted, and to Trinity Hall, Cambridge, where he directed plays.

Hytner is Jewish, though not orthodox. He is also gay, but ambiguously so. ("I believe very strongly that the categories are meaningless. My fear is being thought to have something to hide.") His early work in opera included memorable productions of Handel's Xerxes and Mozart's The Magic Flute. His Shakespeare was admired by actors as well audiences. John Wood, who was Hytner's King Lear, says: "Great directors are like ideal parents, nursing the actors, being wonderfully loving and gentle and tactful. I adore him."

Hytner directed Alan Bennett's greatest hits at the NT, and when he made The Madness of King George, his first feature film, it was nominated for four Oscars. He confesses that his first work at the English National Opera was awful, and his latest film, Centre Stage, bombed. His critics say he is tempted to go over the top. Jeremy Sams, a regular collaborator, attributes this strain of showbiz vulgarity to his Jewishness, "that combination of high ambition and schlock". But there is nothing in his record that he might want to hide.

As the director-designate at the NT, his greatest weakness is that, unlike his distinguished predecessors, Hytner has never run a theatrical company. And there is a list of problems to be faced at the NT. Despite a concerted and well-financed programme to widen access, the audience is getting older. In 1991, 11 per cent was aged 55-64. Seven years later that slice of the age group had risen to 24 per cent. In 1991, 11 per cent of the audience was under 24. By 1998 that had dropped to 6 per cent.

The staff, too, is getting older, with any incentive to move on much reduced by long holidays and good pensions. "Whether it works for Hytner depends on who he surrounds himself with," says the NT veteran. In the theatre business, Nunn's inability to rejuvenate the administration is considered his biggest single failure.

Hytner treads cautiously. He talks of creating a tight little group who will be in the room with him, and he admits: "After 25 years it's inevitable that its mechanisms stiffen." He describes the NT as a fine old clock that needs to be lovingly taken apart before being put together again. But it requires new parts, too. Nick Starr, who administered the Almeida theatre until recently, is identified as a new part.

But the greatest challenge is to get younger bums on seats. Hytner talks about concentrating less on the classical English repertoire and more on work that originated in studio theatres in the Nineties. He mentions playwrights such as Martin McDonagh (The Cripple of Inishmaan), and Mark Ravenhill (Shopping and Fucking). Hytner's production of Ravenhill's Mother Clap's Molly House is in the repertory now. It is a strange piece, like gay music hall, and Hytner says it draws the sort of heterogeneous audience the NT will aim to attract.

"I'm more interested now in what other people are doing than in what I'm doing myself," he says. This means encouraging young writers and directors to make big statements on the Olivier stage. He would say that, naturally, but the clue he lets slip about his term is that the young writers he admires are "unabashed entertainers". It's showbusiness: high ambition and schlock. Very Hytner.