Helen Mirren isn’t just a bobby twin – she’s The Chief.

For someone who specializes in sexy, mistress-type movie roles (“The Cook, the Thief, His Wife and Her Lover” and “Excalibur”), Helen Mirren scores one for feminists Thursday night. She appears as Detective Chief Inspector Jane Tennison, in “Prime Suspect,” a four-hour drama starting on PBS’ “Mystery!” series at 9 o’clock. It’s a role one would expect to find a man playing, which is why Mirren, with bobbed hair and tailored suits, considers it, as she says, “both important to me and women in general. In police departments, both here and in England, women have been relegated to caretaking positions, although I understand there’s one chief somewhere in America. But there’s a level above which they’re not permitted to rise. I’m sure you’d never find one heading a serial killer investigation, as my character Jane does in ‘Prime Suspect’.” Mirren, who also starred opposite Bob Hoskins in the gangland thriller “The Long Good Friday,” maintains a flat in London, but was speaking via phone from her second home in Los Angeles, which she shares with American director Taylor Hackford, a relationship that has lasted six years. She stresses that she’s primarily a film and theater actress, having played numerous Shakespearean roles during her tenure at the Royal Shakespeare Company. “But in terms of TV roles,” reports the soft-spoken actress, “you don’t get many like this. Tennison is extremely intelligent, dedicated and ambitious; her career is everything to her.” But, Mirren adds, “she’s also extremely feminine” conceding that to the policemen whose world she has invaded, “You’re either a dyke or you slept your way to the top. Still, manly-looking women with power are sexy to some men.”

“Prime Suspect” was written by Lynda LaPlante, who spent months with women on the force researching the series. According to Mirren, “It’s been watered down. The reality is much harder, much cruder. But the public wouldn’t accept it. They’d say we were exaggerating. You can’t show people the real thing. They wouldn’t accept it”. “Prime Suspect” focuses on one of the underlying themes of the Clarence Thomas hearings equality in the work place. Tennison has been overlooked time and again, not because of her qualifications, but because of her sex. When she’s finally given the position she deserves, she comes up against a wall of “good ol’ boys” who see her as an intruder. “They don’t want you there,” comments Mirren. “They don’t want you in their club. They have ways of making it hard for you.” Mirren recalls only two roles close to Tennison, where she stepped into the world of men and had to order them around. One was Queen Margaret in Shakespeare’s “Henry VI,” where she became a general and led an army into war. And then, too, there was “Cleopatra,” which she calls “the best just a bobby twin – she’s The Chief role ever written for a woman. Shakespeare gave her great intelligence, ruthlessness and no sentimentality.”

For her role as Chief Inspector Tennison, Mirren had to cut her hair, which, to her surprise, she found “very liberating. It felt wonderful. It’s also useful with each snip I got into the character. You can’t be a policewoman and have long hair. They won’t take you seriously. It’s a sexual statement as far as men are concerned.’ “During my research for the role,” she relates, “I spent time with women on the force in London and got many good tips. Not just the hair, but the clothes. You must be incredibly careful about what you wear. The clothes must be tailored; you can’t be experimental or fashionable, but still not too unfashionable and dowdy. And your neckline can never be too low. “Too, you can never cry in front of the men. It doesn’t matter what happened. Even if your dog got run over. It’s all right if men cry. But if women cry they pull you down. It’s a sign of weakness.” In posing for promotion pictures, the actress reasoned that folding her arms would be a “strong, forceful image.” She was wrong. As one policewomen advised her, “never fold your arms. It’s defensive. Men notice it because they’re trained to read body language.”

Mirren was born in London, the daughter of a Russian father and an English mother. She got her start in the Old Vic’s National Youth Theatre in London and had no problem identifying with Jane’s ambition and drive. “Especially the early part of my career,” she recalls. “An actor must be completely obsessed and motivated. It’s the only way to success and a career.” She has paid a price, she admits. But the image of being an uncomplaining wife left alone in the country somewhere to rear children didn’t appeal to her, either. “That’s why they cry a lot, run to psychiatrists and are all on Valium,” she said. “Work is sexy. Even garbage-men appear to be having a good time working.” As for marriage, she doesn’t think she’s the marrying kind. “It’s an individual thing,” she explained. “I never felt it was a good idea for women. Men should marry each other”. Still, marriage has changed. I’m not sure I feel the same way today. I’m older and wiser. I wouldn’t make a judgment now.” In Italy, she filmed E. M. Forster’s “Where Angels Fear to Tread,” in which she plays a middle-class English widow who travels to Italy and falls in love with a young, Italian boy. “She’s a totally different kind of person from Jane Tennison,” she explains. “This one is silly, romantic and enthusiastic. It’s a story about the foolishness of the English where foreigners are concerned. They’re enamored by them in a wrong way, in a sentimental, romantic way. It’s an arrogance, very much the old Empire mentality.” When she’s asked the oft-repeated question about the quality of roles for women, Mirren replies: “They won’t get better until roles for women get better in life.” Her role in “Prime Suspect,” then, is quite an exception.