Deborah Warner has been having a simply ghostly time staging Britten's `Turn of the Screw'. Mike Ashman went along to rehearsals for a brief colloquy

The ghosts of The Turn of the Screw hold no fears for director Deborah Warner as she and Benjamin Britten's opera (based on the Henry James novella) make their joint debuts with the Royal Opera at the Barbican tonight. And talk of Britten's 1954 chamber opera nowadays can summon up more spectres than just the ghostly duo of the late Peter Quint, ex-master's valet, and "the lovely" Miss Jessel, the children's former governess. Current interpretationitis would have us believe that maybe it is the Governess (Miss Jessel's replacement) and not Peter Quint who is the devil who kills the boy Miles. Or that the ghosts themselves have been "free" (as Myfanwy Piper's libretto has it) with the children in a way that parallels the so-called revelations of recent Britten biography. And who believes in ghosts nowadays anyway?

Warner is passionate in attacking those who would make the piece too black and white; unambiguous, if you like, in her belief in what the libretto shouldn't be made to mean. "What I've learnt is that any answering of these ambiguities is actually to be avoiding the piece. The ghosts exist because the children think about them. Clearly their relationship to Quint and Jessel was very intense."

Warner insisted on getting a "proper age" Flora - rarely, if not uniquely, the part is played here by a 10-year-old, Pippa Woodrow. "It is only the adult world that sees their relationship with Peter Quint and Miss Jessel as a bad thing. You can't approach Miss Jessel as a dark, negative, ghoulish force: if she were, Pippa would have been out of that rehearsal room as fast as her feet could carry her. Flora loved Miss Jessel and wants to keep her memory alive."

This realisation has led Warner to some new thinking: "I cannot conclude that Quint and Miss Jessel are black, dark, evil forces; to conclude that is to absolutely not go on a journey with this piece."

She enthuses about how the children (Miles is played by 12-year-old Edward Burrowes) have in many ways led her investigation into the piece, bringing their "own reality" to the experimental work done in the rehearsal studio. "It's also very thrilling to stop a gruelling rehearsal, say `Let's go back to the beginning,' and see someone cartwheel up to the back of the stage to start again. I like the loose cannon aspect of work anyway, and I've made them quite loose - though not musically, of course."

Another contemporary ghost is the autobiographical connection. "I find this trawling through Britten's private life demeaning and offensive," protests Warner. "I'd say it's homophobic, to be quite honest, quite neurotic and profoundly reductive for the artist and for ourselves. In 50 or 100 years' time, people will be shocked and surprised by what was being written in the 1990s, looking at Britten through this frame."

In recent interpretations, the Governess has sometimes been presented as a hysteric, who imagines everything and ends up by almost literally killing her own charge. "It's all got a wee bit too simple," Warner says of such character analysis. "She is having a huge fantasy about her new place in the world, and actively thinking about the children's guardian [the unseen young man who employs her in the opera's Prologue]. Peter Quint picks up on this and comes to have a look at what is quite a sexual scene - there she is, lying about on the lawn, dreaming possibly her first erotic thoughts. So involved is she, she makes the mistake of thinking it's the guardian - which is quite a mistake. I think she feels guilty about that, and that guilt spurs her on. Then she sees the man again and is told she has seen a ghost. She has reason to be highly strung..."

Warner interrupts herself to preview a detail of her stage blocking. "A lot of people will hate the fact that Quint appears at the bottom of the tower around which the Governess has just moved - infinitely more phallic and revealing. The fact that the entire audience knows that Quint will appear up the tower makes it profoundly necessary for a generation that he doesn't - because..." and here Warner starts to laugh... "this is called `what we do'."

Just before Miles's death at the end of opera comes his cry of "Peter Quint - you devil" and the Governess's claim, "Together we have destroyed him." Both are moments of profound and possibly ambiguous resonance that have excited recent interpreters determined to nail the work down to specific emotions.

"Miles faints," comments Warner, "in the difficulty of taking on two realities - the impossibility of living them kills him. Quint does go `away for ever' [as the Governess has promised Miles he will] and Miles dies - because it's half of Miles! Maybe Peter Quint never existed - but Miles's imaginative experience with the spirit and the essence kills him."

Although Warner admits "I like doing opera more and more", her main work continues to be in the spoken theatre, albeit in increasingly fluid forms: "I like the grey area between things - where a poetry recital becomes a dramatic performance." One on-going project, as yet unseen in the UK, is a tour of TS Eliot's The Waste Land in selected cities around the world, where she chooses venues to fit the piece, not necessarily standard theatres at all.

This "exploiting the property of space, working on your feet in an unprepared design way" may seem the very opposite of the ordered Victorian world that many previous productions of Britten's opera have inhabited. In fact it had a big influence on the setting that Warner and her design team of Jean Kalman and Tom Pye have come up with.

She was excited by a visit to the Barbican earlier this year when it was a hard-hat site and the RSC's raked stage was being removed. She saw that the two huge brick columns at the back of the stage that have annoyed many occupants of the space were "in a very abstract way, the two towers that Henry James describes in his novel". From this began the idea of "a dead space in a dead theatre, like it looked during the building. An imaginative area - a space that belongs to the children and the ghosts, and which makes Mrs Grose [the old housekeeper] and the Governess the visitors."

Warner has been excited too by her rehearsals and cast. "My favourite thing at the moment is directing children, and highly accomplished adults like this bunch, who have gone on an amazing journey with me." She apologises to Britten and Piper for having thought initially that their scheme of two humans, two children and two ghosts might be limited or dated. "I feared I wouldn't be able to be as free with it as with Shakespeare, but you can bounce ideas off it endlessly. This is as good as Shakespeare - that's saying a lot, isn't it?"

Before final rehearsals, she was just starting to re-read James's novella: "It's given me all my notes - my own notes on my own production. When you've lost the story a bit or when your psychological detail is not as acute as it should be, just go back to the James." She quotes a phrase used by the Governess in the novel - "the fancy of our being lost as a handful of passengers in a great drifting ship"... "Fabulous - and that's what the Barbican is with this cast: the six of them rattling about in this vast black void. I've had a lovely time."

Opens tonight, 7.45pm Barbican Theatre, London EC2 (booking: 0171-304 4000) and in rep to 11 Oct