A play of desire or perversion?

In the foyer of a suburban theatre, a small band of provincial critics mills about, looking slightly shell shocked, eyebrows raised as they struggle to gather their thoughts. "I don't think he's a paedophile," offers one girl, cautiously. It's not your average opening gambit, but then we have just seen Blackbird.

In any discussion of David Harrower's play avoiding references to paedophilia is about as difficult as dodging puns on the author's name.

"People think this is a play about paedophilia . . ." said Carole Winter, the producer. "But it's absolutely not that." (See?) Having already seen the script, I was inclined to contradict her. There seems little sense dissembling about the central topic of the play, and even a casual glance at the poster is likely to give you the wrong' idea: girl on bed, damaged stare, man clad in black, in the dark, and so on (see right).

But on the stage, I confess, Blackbird does come over rather differently.

Former lovers Ray (Robert Daws) and Una (Dawn Steele) are reunited some 15 years after a passionate affair. There is the usual tension, shouting, crying, general recrimination and throwing of chairs. The only anomaly being that Una, at the time of the relationship, was 12.

It's a tough subject for any playwright to tackle, but Harrower insists "I never looked at it objectively and told myself I'm writing a play about sex-offending.'" It is clear from his sympathetic portrayal of both characters that "they are two lovers. They've shared something which only the other can understand".

So the dread pae-' word, with its hysterical Daily Mail-reader connotations, is never once mentioned, and the play is the stronger for it. Also, Una is now 27: so, for most of the play, there is none of the usual context' of seeing a grown man with a young girl.

But it's hard to miss the fact that Steele is lightly set, girlish. Her Una is slightly (and appropriately) imbalanced, both in gesture and voice. She flirts and squirms, almost simultaneously.

And from the stalls, Daws looks a lot like Roger Allam (guess who played Ray in the London show?). I put this to the director, David Grindley.

"Nah, Roger Allam's almost heroic; but Robert's career has been made out of playing ordinary Joes."

The (s)ex-offender is a typical middle-aged, overweight man, with a dull job, wearing short sleeves and with a phone stylelessly hooked on his belt. In other words, he could be anyone's dad. Which is half the horror. Blackbird makes you question everything. And then question your questioning.

Grindley echoes Ray's own defence: "This man doesn't have perverse sexual desires, but in a particular set of circumstances finds himself in the grip of a desire he has to act on . . . What I call an Ian McEwan moment' - one thing happens and changes everyone's lives."

Mistake' has rather generous implications, but it is clear (or appears to be) that Ray was not grooming kids methodically. It's not a legal defence, of course; but for many viewers the problem won't be one of law, anyway - unequivocal on the issue of sleeping with 12-year-old girls - rather of moral repugnance.

This is where the play hits home, forcing the audience to acknowledge that the 12-year-old Una was compliant. In fact, part of the play is watching her be compelled to acknowledge this. Ray fell in love - in whatever mangled form - with a 12-year-old girl. But she wanted him to be her boyfriend. Does this count for anything? In court, no; on stage, certainly. And isn't this one of the points of the theatre - to enable us to confront things in thankful abstraction from the horrors of reality?

Not everyone will be that thankful, of course. The pair of old ladies next to me shuffled awkwardly throughout. One was permanently clock-watching. The other appeared, literally, to attempt to fall asleep in order to avoid what was unfolding. When this didn't work, she took out a miniature, and proceeded to drink. I suspect, however, that this says all the right things about Blackbird. The play is not intended to be a cosy afternoon's entertainment. But it is memorably intense: one-act, relentless, gut-wrenching in the entirely non-hyperbolic sense. I've never seen so many theatre-goers sitting bolt upright - braced even. Except when the audience was gasping, you could hear the breathing of the actors, 30ft away.

If nothing else, it is always good to be reminded that this level of reaction can be achieved by just two people on a more or less empty stage - credit due, here, to Jonathan Fensom's bleak and claustrophobic staging.

Harrower knows the challenge his play poses ("Did anyone walk out?" he asks), but Blackbird has undoubtedly done its job. Having picked up an Olivier Award, it has been staged in the West End; in New York, with Jeff Daniels as Ray; by Cate Blanchett in Sydney; and now chosen by Peter Hall as part of the inaugural season of the Rose Theatre, Kingston.

Some theatres still won't touch it, but those who will - nine on this tour alone - have found that there is invariably a strong, and generally positive, response from the audiences.

After one show, Daws tells me, grinning, a friend of his overheard one woman snap at her companion, "Don't talk about it." And then, almost immediately, two gents in the loo: "Sex on stage, eh?"

"Quite so."

Quite so, indeed. So much for critics.

Blackbird is at the Oxford Playhouse from Tuesday until Saturday, April 26. Box office: 01865 305305 or visit www.oxfordplayhouse.com. There is a post-show talk on Wednesday.