Petula Clark played the role of Norma Desmond in London's West End in Sunset Boulevard for more than a year. The Grammy-winning singer even held the part of the sadly deluded movie star when the production closed in 1997.

You figure that would prepare her for life on the road when she signed to star in the touring version of the Andrew Lloyd Webber musical. Instead, the veteran entertainer found herself having to relearn a role she thought she knew inside and out.

New cast members. New sets. In Susan Schulman, a new director. In other words, a new take on the show.

"The first few days of rehearsal were quite interesting," Clark says. "As soon as I started saying a line, I would walk to a certain place. Susan would say, 'No, darling, you don't go there.' I would start to say, 'But in London . . .' And she said, 'Darling, we're not in London.' "

Ouch. But despite a bumpy beginning, Clark reports little friction between director and leading lady.

"Oh no, that didn't last long," Clark says with a giggle. "We had a few laughs about it afterward. It was a very interesting experience, like learning and unlearning at the same time."

Some things to unlearn included the mammoth, darkly imposing set that was a hallmark of the Broadway and London productions. When Sunset Boulevard initially hit the road in 1996, the sets were intact but the show featured non-star Linda Balgord as Norma. That tour ended prematurely after losing a fortune, causing producers to revamp the concept: Cast a star and shrink the sets.

"The set is different," Clark confirms. "I still have to go up and down those damn stairs, though. But now it's more about the people and less about a set." The new production is more expressionist. It's set on a Hollywood sound stage, giving the play a dreamlike quality as opposed to the hard-bitten reality of the original. Clark says her Norma is also different from the way she performed the role in London.

"There's no blueprint on how Norma should be played," she says. "It's like Hamlet. It's one of those great roles. Every actress has whatever she's got in her and it will come out in the performance. We're all saying the same words and singing the same songs and climbing the same stairs, but it will always come out a little differently." Despite following such formidable talents as Glenn Close and Betty Buckley in the part, Clark's reception has been enormously positive. The 60-something performer has won some of the best notices in her long career, both for her work in London and on tour.

Those reviews may surprise naysayers, who continue to view Clark as a cheerful '60s song stylist in go-go boots, warbling effervescent pop hits like Downtown and Don't Sleep in the Subway. The tragic, manipulative Norma is worlds away from that image.

But Clark is no stranger to the stage, having starred in London productions of The Sound of Music, Candide and Someone Like You, for which she wrote the music and lyrics and co-wrote the book. And she starred as the mother of doomed twins in Willy Russell's acclaimed Blood Brothers on Broadway and in the nationwide tour. "Blood Brothers was much closer to me," admits Clark, who has three grown children.

"I know what it's like to be a mother. The last scene with the two brothers lying dead . . . I remember when we first rehearsed, I couldn't get through it. You can't sing when you're crying. You just can't. But the feeling of being a mother was so natural to me.

"The feelings of Norma are not natural to me. Although there's a certain amount of fear, anger and jealousy and hate in all of us, they are things we keep suppressed. In Norma, I'm having to dig out all those feelings. That, in itself, can be quite exhausting."