SUZY Cooper has no hesitation in naming the trickiest role in her stage career, and no, it is not playing principal girl to Berwick Kaler's ever-teasing dame in York Theatre Royal's pantomime.

Her choice is La Marquise de Merteuil, the icily elegant libertine of Christopher Hampton's Les Liaisons Dangereuses, in which she will be appearing at the Theatre Royal from next Saturday.

"It's tricky because of its complexity and because it's the biggest role I've done," says Suzy. "When I played Daisy Gates in Laughter When We're Dead at Newcastle Live Theatre, I was working with Sean O'Brien, creating a new piece and a new character, but something like Les Liaisons is just as exciting and it's more nerve-wracking because people have expectations.

"Some people are obsessed by this play and are very definite about who the characters are. You have everybody else's information about those characters, and it's very difficult to put it all to one side - as you must - especially when all actors are unsure and you're having to put yourself on the line."

Ironically, Suzy had envisaged playing a different role when she first heard that artistic director Damian Cruden had chosen Hampton's decadent drama for the autumn season of saucy plays. "I went out straight away and bought the book of letters that formed Les Liaisons and rang Damian to say 'Please will you consider me for the role of de Tourvel'; he said come along to the auditions and it turned out he wanted me to read for La Marquise de Merteuil instead!

"My reaction was give me another five years to get some gravitas. I thought I was too young for it because everyone thinks of Glenn Close in the role in the film, and so we all assume she's older but in fact de Merteuil was only about 25."

Suzy, who is 32, immediately came around to the idea of playing the "embodiment of the sociology of the late 18th century", as she calls the seductive, blackmailing, duplicitous de Merteuil in the Theatre Royal's autumn season magazine.

"It was the longest wait in my life to learn if I'd got the role but eventually Damian did ring to say yes and that he had a surprise for me," she recalls. "I would be doing another role as well: Tom Snout, one of the rude mechanicals in A Midsummer Night's Dream."

A golden girl playing a simple, gap-toothed boy? No problem, especially as role reversal is second nature to pantomime and Shakespeare performers. The deceptions carried out by La Marquise de Merteuil in the sex-war games of French society in the 1780s represented a greater challenge.

"The way you play her comes down to understanding the character," Suzy says. "When you first read the play, she seems a hideous person, so evil, and it's not until you really get into the character you realise she was a woman before her time, a pre-feminist time.

"She's very avant garde; she feels like a man in woman's clothing and, at the same time, a woman of the future."

Describing herself as a responsive rather than intellectual actress, Suzy says: "In rehearsals, you try to find the truth of the piece: if something feels right, then you go with that. Whether playing this role or principal boy or girl in panto, you have to believe in that moment, no matter what you're doing."

While on the subject of pantomime, there is good news: after television commitments filming Casualty forced her to miss Dick Whittington last year, Suzy Cooper's helium-voiced dizzy blonde turn will be back this Christmas in Jack And The Beanstalk, her ninth Theatre Royal panto.

"Jack And The Beanstalk was the first panto I did here nine years ago, so I've come full circle. I can't wait," she says.

Casualty turned out to be an apt show for Suzy, because she has been starring in a hospital drama of her own, after a stage head butt in Laughter When We're Dead went wrong and her nose was broken.

"I've since had two operations and there's another one to come as I've got a deviated septum. I still can't breathe through one side at the moment."

So that really was a dangerous liaison.

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