Alone With ‘Shirley Valentine’ : * Stage: Veteran actress Katherine McGrath acknowledges trepidation about performing solo at the Old Globe.

“Shirley Valentine,” Willy Russell’s popular one-woman show about a 42-year-old housewife, will be Katherine McGrath’s 20th production at the Old Globe Theatre and will mark her 10th year as an associate artist there.

Still, the actress, who has played everything from Titania in “A Midsummer Night’s Dream” to the activist wife in “The Snow Ball,” admits to having just a bit of trepidation about doing her first solo outing.

“I’m a little nervous,” the red-headed actress confessed in the Globe’s rehearsal room in what once served as the administrative building of the old Naval Hospital in Balboa Park. “I’m trying real hard to convince myself that I’m not nervous, but there’s no one else to bail you out and keep you afloat if you mess up. I have this image of myself talking on and on all night.”

Still, as she has gotten further along in the rehearsal process she does feel that there is one person she can count on to come to the rescue: Shirley.

“She’s such a wonderful character, I feel I’m doing the play with Shirley. It isn’t like being all alone because she’s a really nice person to spend time with. It’s like spending time with a good girlfriend.”

“Shirley Valentine,” which opens Saturday at the Old Globe’s Cassius Carter Centre Stage under the direction of executive producer Craig Noel, drew raves for actress Pauline Collins when she did it on the West End of London in 1988, on Broadway in 1989 and in a film version, also in 1989. What makes those successes so remarkable is that there is nothing remarkable about Shirley. She is an unpretentious Liverpool housewife whom we meet when she is in the act of cooking an egg-and-chips dinner for herself and her husband, and talking to the wall in the process.

It’s what she tells the wall--about her life, about her hopes, her dreams, her realization that there is so much more to life than she has experienced so far--that makes the play.

In some ways, McGrath, who has never married, seems to be the antithesis of stay-at-home Shirley Valentine.

McGrath, who lives in Ocean Beach, has a cabin in Vermont, and divides her time between San Diego and her work elsewhere, particularly in Los Angeles.

And yet there are similarities. “She is kind of regular like myself,” said the unpretentious McGrath, who wears very little make-up and came to the interview dressed in simple, worn-looking sweat clothes that seemed thrown together.

“I imagine everyone--men and women--have a little of Shirley Valentine in them. She’s so universal. She’s just searching for what made her who she was, and how she ended up as who she is.

“He (Russell) is a wonderful playwright. He was a hairdresser, and I bet he listened to so many women bitching and moaning and telling stories, that that’s why there’s something so real about the play. I bet while he was snipping away at their hair, he was turning the phrases.”

McGrath also finds herself asking herself the play’s central questions about who she is and how she ended up as she is. For, as much as she enjoys her career, which has spanned stage and screen, she does have her own unsatisfied longings.

“My biggest regret is that I never had children,” she said softly. “I would have loved to have a little family. It’s one of those things I felt I had to give up. Theater is a jealous mistress. It takes you away from your loved ones.”

McGrath compensates by going home often to Marblehead, Mass. where she was raised and her older brothers still live with seven nephews and nieces.

She is the only one in her big Irish family to turn to a career in the theater. Her father was in real estate, her mother was a housewife. In her senior year of high school she was preparing to go to Georgetown University School of Foreign Service. Then her drama teacher cast her in “Twelfth Night.”

“It was like putting on a dress that fits you right,” she said with a grin. “I loved it, and it seemed it would be nice to do something for a living that you loved. So with the help of my drama teacher, I went to the Boston Conservatory instead.”

The Royal Academy of London followed, and then New York, where McGrath still has an apartment (now occupied by one of her nephews). In 1978, while in New York, her longtime friend Lindsay Law, now producer of PBS’s American Playhouse, heard from his friend, Jack O’Brien that O’Brien was having a hard time finding a Titania for his production of “A Midsummer Night’s Dream” at the Old Globe.

Law recommended McGrath, and she got the part. McGrath and O’Brien hit it off immediately and four years later, McGrath became one of the company’s first associate artists.

She moved to Los Angeles but within a few years got tired of shuttling to San Diego on weekends. So, eight years ago, she moved to Ocean Beach and instead started shuttling to Los Angeles as needed.

With 19 shows at the Globe behind her, she’s been kept pretty busy in San Diego, so far. She expects that she probably will do a show this summer at the Globe, as well.

“I remember thinking (the Globe) was a theater where you could afford to take chances,” she said. “You were encouraged to do the play the way you chose and the way it was directed.

It seems to me (the Globe is) as close to a repertory company as we have. You work with a certain percentage of people on a show that you’ve worked with here before.”

* Performances of “Shirley Valentine” begin Saturday and run 8 p.m. Tuesdays-Saturdays and 7 p.m. Sundays with Saturday/Sunday matinees at 2 through April 26. Tickets are $17-$29.50. At the Old Globe’s Cassius Carter Centre Stage, Balboa Park, 239-2255.