Bo may be teacher's pet now in the John Derek finishing school for young stunners, but former star pupil Linda Evans isn't complaining. At 37 she's a cum laude graduate. With two marriages behind her (the first to Derek, the more recent to Hollywood real estate mogul Stan Herman), the 5'8" Bo look-alike has finally taken her career in her own hands. Currently that means playing Steve McQueen's earthy schoolmarm sweetheart in the recently released Tom Horn. No matter that the part required Linda to wear a gold tooth and shatter forever the baby-doll image nurtured by Derek; she couldn't be happier. "I've always been protected by men," she says. "Now I feel I'm in charge of my life."

Painfully shy as a child, she was born Linda Evenstad in Hartford, Conn, and moved to North Hollywood at the age of 6 months. Her father was a painter and decorator, her mother a housewife. "I grew up just trying to cope," she says. At Hollywood High, an actress friend, Carole Wells, dragged her to a casting session for a commercial. She got the part, appeared on TV's Bachelor Father and went on to sign a $250-a-week MGM contract. In 1965 she won a continuing role on ABC's The Big Valley, plus the attention of movie producer John Derek. "I was so excited I could hardly breathe," Linda recalls of their first meeting. "My mind went back to my teenage years when I had a picture of John over my bed. I had spent years looking into those eyes."

Before long Derek split with wife Ursula Andress after her publicized fling with Jean-Paul Belmondo and took up with Linda. "It was the most wonderful life I can imagine any woman having," Evans recalls nostalgically. "He would spend months handcrafting a vest or boots for me. Then he would wait for me to come home and have champagne and grapes individually dusted with sugar next to a fur bed he had laid by the fireplace." Nothing makes Evans angrier than the suggestion that Derek is an exploiter of women. "He cares about beauty more than anyone I've ever known," she says. "He would have made a wonderful knight of the Round Table."

Alas, the Camelot she shared with him did not endure. In 1973 Derek went to Greece to make a film with a 16-year-old actress called Mary Cathleen Collins. "I can't describe what it is like to arrive on location weeks later and be told by a man you have shared everything with for almost 10 years that he still loves you, but that he is also in love with somebody else," says Linda. The story that Mary Cathleen (now Bo) tells is that Linda took the news like an angel. "I don't remember being angelic," says Evans with a wry laugh. "I remember some yelling and screaming on my part and being very hurt. But if that's the way Bo prefers to remember it, that's all right, too."

Her marriage shattered, Linda limped home to Hollywood to put her house up for sale. One of her first callers was Herman. "Stan was warm and generous and not at all pushy," she recalls. "I was with him for two years before I felt sure enough of the relationship to call John and ask for a divorce." She and Herman were married in 1976; they separated more than a year ago, in part because she wanted a career. "Stan still makes my heart jump when he enters a room," she says. Living now in a $750,000 French Provincial cottage in Coldwater Canyon, Linda is preparing for her role on ABC's new Oil series this fall. "The woman I play [a tycoon's wife] just follows her emotions, not using her head at all," Evans says. "I love the part because I was there once. I hope the character will grow just as I have."