Guilty or not guilty?

People come to The Accused to stare at me, but within five minutes they forget I'm there and they're into the story. The question is: did Mr Sherwood, a heart surgeon, poison his wife? At the end of the first act you should consider he is innocent, then guilty at the end of the second, and be without a blooming clue by the end of the third. Then what happens is that you, the jury, decide.

I'd long wanted to write a play with the audience as the jury. What we hadn't expected - and it has happened everywhere we have toured around England - is how involved people get. There is a point where Edward de Souza, who plays the Jury Bailiff, tells the audience, "I will now leave you to discuss among yourselves." The place just bursts into a riot while everyone goes, "I think he did it... No, no, I think there wasn't enough potassium chloride and I never believed the girl", or "No, no, the girl is telling the truth." Then they vote. Recently in Coventry it was four-all: four guilties and four not guilties. In Windsor we even had a tie - 256 votes each. When you get the result the booing and cheering and screaming starts because everyone who's got it wrong gets annoyed, and everyone who gets it right starts cheering. Then the play goes on for another six minutes when you discover the real truth, and the whole place erupts again.

I've been very touched by the reviews. I've never acted before. It's been a terrific learning curve, but sharing a room with Tony Britton (who plays Mr Justice Cartwright) means I've had a masterclass every night now for six weeks.