ACTOR Timothy Watson knows he's done his job properly if audiences leave the theatre looking like they've seen a ghost.

For the stage phenomenon known as The Woman In Black is a haunting story designed to give people the fright of their lives. Over two million theatregoers have experienced the play, both on tour and in London's West End where the production is in its 16th year.

Watson and Robert Demeger are teaming up again for the latest tour, which plays Darlington Civic Theatre next month. The pair have previously starred in the play - adapted by Stephen Mallatratt from Susan Hill's bestselling novel - both in London and on tour.

"It was a successful partnership and we wanted to do the play together again," says Watson. "It has just two actors and the chemistry between them is very important. The margin for error is very small."

The ghost story has Watson's actor engaged to exorcise the spectre of a woman in black by a lawyer (Demeger) obsessed by the curse he believes has been cast over him and his family.

It was first staged at the Stephen Joseph Theatre in Scarborough, although Watson's first brush with the ghostly goings-on was in London.

"I was completely knocked out by it," he recalls. "I thought it was a sensational piece of theatre because it has all the things that, from an actor's point of view, are so enjoyable.

"It's not a grand show, dependent on big sets, and is driven by the two actors. It's a piece of theatrical storytelling and people are very sceptical about two actors on essentially a bare stage.

"It's very refreshing as an actor to get an empty stage and know it's up to us. We're the centre of attention for the audience because they're not looking at a glossy set."

There's no doubt the production has a shocking effect on audiences. "On many occasions I've seen grown men leave the theatre absolutely quaking in their boots. We know it's a job well done," says Watson.

"That's one of the wonderful things, particularly being on tour, as each venue has a different feel. The venue plays an integral part in the show.

"The actual events of the play take place in the theatre. Each evening is different because any group of people has an effect on other members of the audience, the symbiotic thing of sparking off each other. You find if people start reacting in a particular way early on, it's infectious and spreads all round the audience. Some are stunned into silence, others giggle nervously.

"At one point in the second half, when the heat gets turned up, I've done quite a few shows where we've had to wait for them to calm down because they've jumped so far in the air and have to check how their friends are."

He feels the shocks are comparable to the scary bits in horror movies. The effect must be similar to how audiences reacted the first time they saw Alfred Hitchcock's Psycho. The ghost story appeals to people's fears about things that go bump in the night, what's behind a locked door and the sound outside you can't quite make out.

Theatregoers aren't the only ones who are scared. Watson feels that way too at every performance. "It's very difficult to convey to the audience if I don't actually feel scared witless and convey my character is beside himself with fear. I get goosebumps and break out in a sweat every time we do it," he says.

Hill's book has been filmed for TV and heard on radio, but he feels the theatre version is the most effective. "It worked well enough elsewhere but nothing like it does on stage because the audience is literally haunted themselves and come to realise that," he explains. "Of course, we can never tell how well they sleep when they go home."

He recalls an extreme reaction from a teenage girl who saw it in the West End. "Afterwards, she came to the stage door with her teacher and was really scared, traumatised even. I showed her round the stage with the ordinary lights on and showed her how one or two of the things that had frightened her worked," he says.

Touring has alerted him to the ghosts haunting theatres up and down the land. "The Theatre Royal in Bath, where I toured before, has a famous and active ghost, but I didn't see her," says Watson.

Legend has it that the ghost of Darlington Civic's first manager, Signor Pepi, still roams the aisles and dressing rooms. Perhaps he'll be waiting for Watson.

l The Woman In Black is at Darlington Civic Theatre from September 12 to 17. Tickets (01325) 486555