How to get from Shaw and Gielgud to 'Shopping and F***ing'

Sir Richard Eyre, doyen of British theatre, has produced a history of 20th-century stagecraft. It won't please everyone, he tells Louise Jury

To conjure up the distinguishing thrill of theatre, Sir Richard Eyre, one of its finest magicians, tells the story of a rare snowfall in Florence. One of the Medicis is said to have commissioned the mighty Michelangelo to create a sculpture in snow. It is reputed to have been his greatest work, but its glory was ephemeral. You had to have been there.

To conjure up the distinguishing thrill of theatre, Sir Richard Eyre, one of its finest magicians, tells the story of a rare snowfall in Florence. One of the Medicis is said to have commissioned the mighty Michelangelo to create a sculpture in snow. It is reputed to have been his greatest work, but its glory was ephemeral. You had to have been there.

Eyre believes theatre is exactly the same. "It's live, it's unrepeatable," he says. So the irony is not lost on him that for the last two years he has been working on a project to tell the history of 20th-century theatre through the anonymous medium of television, using film to convey, inadequately, the magic of past theatrical landmarks such as Peter Brook's A Midsummer Night's Dream. (The clip is a revelation to anyone not lucky enough to have seen it in 1970.)

Yet Eyre had readily agreed when asked by the BBC to write a major series for the millennium. It seemed a suitably grand project to fill the gaping hole left by his departure from the Royal National Theatre in 1997, after 10 remarkable years as its artistic director. And it offered the opportunity to interview the most distinguished figures in theatre - from Sir John Gielgud in one of his final interviews, through the actors Dame Judi Dench, Sir Ian McKellen and Liam Neeson, directors Peter Brook, Sir Peter Hall and Stephen Daldry and writers Arthur Miller, Sir Tom Stoppard and Harold Pinter - to present what Eyre calls "a personal view" of 20th-century theatre.

After consulting the Australian art critic, Robert Hughes, Eyre decided to write a book first to get his thoughts in order. "You don't think about theatre normally, you just do it," he explains. "Everywhere I approached was familiar territory, but in the writing about it, the landscape became infinitely clearer."

He thought he should start with an argument, "about why we should be interested in theatre, why it has been important and why it will continue to be important forever," he says. "And of course, it has to start with Shakespeare, because Shakespeare is the DNA, the miraculous accident of British theatre."

From there, Eyre moved to a realisation - "not an original thought" - that for the 300 years following the Restoration, the British theatre owed everything to the Irish (Sheridan, George Bernard Shaw, Oscar Wilde). Chapters on American theatre, the bombshell that was Look Back in Anger in 1956 and the influence of Beckett and Brecht followed.

Eyre, who collaborated with fellow director and writer Nicholas Wright, acknowledges that some critics will hate their emphasis on Brecht or the championing of the much-neglected plays of DH Lawrence. But he says: "We're at some pains to call it a view, not a history. It's partial, not comprehensive: there will be some things that will really annoy people." For a man marked by a gentle courteousness and a diffident charm (he winningly claims he went into directing because he quickly realised his limitations as an actor), you sense offending people is not something he does lightly. Yet Eyre can be fiercely and suddenly passionate about those things which matter to him. He makes clear that, as a BBC governor, he has been critical of the BBC's recent deficiencies in arts programming.

He goes on to ridicule the government for putting money into the arts but refusing to back them publicly. He laments that Tony Blair shakes hands with the pop star Noel Gallagher but, for apparent fear of the Daily Mail and tabloids, will not say, "This is your heritage, this belongs to you and this [arts subsidy] is done on your behalf."

Yet he regards the current reports on a crisis at the National as unfair to his successor, Trevor Nunn. Eyre says that "of course" artistic directors step in to sort out a production that looks set to fail, as happened recently with Romeo and Juliet and Peer Gynt. "The ultimate responsibility is to the audience," he says. Nunn was, perhaps, unlucky that his interventions were so conspicuous, but Eyre says it has happened in the past. Gentlemanly, he refuses to name names.

Eyre describes himself as a "genetic melancholic" but is optimistic about the future of "the most human of all the art forms' and even moots the possibility of returning to run a theatre (though not the National) one day. But first, he has to complete his debut feature film, the love story of the writer John Bayley and his late wife, Iris Murdoch.

In the face of repeated predictions of theatre's imminent demise, Eyre insists there is much to be hopeful about, not least the roll call of talent including the directors Sam Mendes, Stephen Daldry, Matthew Warchus and Complicite's Simon McBurney, as well as writers such as Patrick Marber and Mark Ravenhill.

He says he does not know whether theatre will survive in the form we know it now. "But I know that an art form that depends, at its heart, on live people and live audiences will survive. Unquestionably."

'Changing Stages' starts tonight on BBC2 at 7pm. The book to accompany the series is published by Bloomsbury at £30