Diana Rigg arrived on American television in 1966 as long-legged, jumpsuited Emma Peel, specialist in karate chops and swift kicks and partner of Jonathan Steed (Patrick Macnee). Together they were known as The Avengers.
Beautiful, steely and forceful, she followed Honor Blackman, who originated the role in Britain, and was an instant hit. But for a young woman trained in classical theatre, the series was merely a diversion.
Shortly afterward, she joined the British National Theatre headed by Sir Laurence Olivier, who called her ''a brilliantly skilled and delicious actress.'' A critic gushed that she was ''England's emergent superstar.''
Today Diana Rigg is 52, still lithe and assertive, but American television audiences see her rarely. For a few moments each week, she turns up in her second season as the genteel host of PBS's Mystery! (Fridays at 9 p.m. on Channel 18).
She recently accepted from Princess Margaret a citation from the British Crime Writers Association honoring the series and its funder, Mobil Corp., for ''10 successful years.''
But since the birth of her daughter Rachel, now 13, Diana Rigg has developed strong views about television content. She believes that parents need to take a close look at what their children want to watch.
''Television has the power to influence for good _ a great deal of good _ and also has the power to influence for not so good,'' she said.
''I think it's unfortunate that the bias is largely toward the latter, and that because the majority of people like to sit in front of the television and be anesthetized in one way and another, they aren't given good programs that teach and inspire. Commercial companies play to the lowest common denominator, and I think it's very sad that it happens that way.''
On the other hand, she acknowledges that there are programs worth watching, and she believes that ''it's absolutely vital that an alternative channel exists that at least keeps some standards flying.''
But much of what is shown both in England and North America is what Rigg called ''rubbish,'' programming that airs largely because ''people have been brought up not to expect better of television.''
Like many actors, even those who appear on the tube, Rigg watches little television at home.
''I tend to watch the good, much as you'd pick up a book to read or you'd go out to see a particular film. That is the way I treat my television, the way you'd choose a particular piece of music to play.
'I think if parents brought up their children to be selective about television, possibly television might take a quantum leap forward _ who knows? Instead of which, they use television as a soporific for the child. They shove the child in front of the television and know it'll keep them quiet.''
One program that was no soporific was the fascinating 11th-season opener of PBS's Mystery!, the four-part Mother Love, starring Rigg herself. Her performance, as an obsessive mother who goes mad with jealousy and hate, won raves both in North America and in England, where she was awarded the BAFTA, the British equivalent of a combined Emmy and Oscar.
In Mother Love, she said, she wanted to add an imperious note, a sort of tension to Helena Vesey, a woman Rigg described as having her ''lid on too tight.''
The formidable Rigg also knows what she wants out of a production. In this case, she wanted to light up Helena's eyes.
''I had a little tussle with BBC Lighting over the closeups,'' said Rigg. ''Nowadays they tend to do a sort of blanket lighting, very much bounced-off-the-ceiling lighting from above. I got on extremely well with the cameraman, but I did finally get what I wanted, which was lights in the eyes.
''The first two episodes, I said, 'Do what you want, but certainly episodes three and four, puh-LEASE give me SOME-thing to light my eyes, because that is the only way you can read what is going on in the mind.' And I won my battle.''
It isn't difficult picturing the strong-willed Diana Rigg winning her battles. A veteran of the Royal Shakespeare Company since she was 20, she can intimidate with the inflection and delivery she developed there.
Yorkshire-born Rigg entered the theatre over the disapproval of her parents, who had sent her from India, where she had lived since infancy, to boarding school in England at age 7. She recalls her childhood as happy _ her father was overseeing the building of the state railway at Jodhpur _ but after her mother returned to India, Rigg did not see her for 18 months.
''Bizarre,'' she says now. ''It's a long time in a child's life, at 7. I loved her very much, but she was quite a stranger to me when she returned. My father was even more of a stranger, because I didn't see him for two years. I think it probably did leave its mark.''
Like many a lonely child, she turned to the world of imagination. At 11, she portrayed Goldilocks in a school play; when she was 14, Emily Bronte. At 17, over parental objections, she enrolled at the Royal Academy of Dramatic Arts and in 1959 was admitted to the Royal Shakespeare Company.
But it was her 30 months playing Emma Peel in The Avengers (March 1966 to September 1969 on ABC, still showing on Arts & Entertainment) that brought her international attention.
The role lead to Diana, an NBC series she later called ''dreadful,'' and appearances in several dramatic specials on CBS. She also played the only woman James Bond ever married, a Spanish contessa, in the 1969 film On Her Majesty's Secret Service, starring George Lazenby as Bond.
Three years after her divorce from Israeli artist Menachen Gueffen, in 1974, she gave birth to a daughter by Archie Sterling, whom she married in Manhattan in March 1982. (They are now separated.)
It was Rachel for whom she made what she called ''a bit of a bargain,'' to curtail her acting career.
''It's how you view motherhood, and how important it is in relationship to your career,'' she said. ''I consider it rather more important than my career.
''If I was in a play which ran for six or nine months at the West End, then at the end of that I would not work for a while, so that she could see the end and know that I would be with her all the time after. She understands. I try and keep the holidays free, Christmas holidays and Easter.
''But I've never gone, since she was born, from one thing to another to another. Never, as a matter of policy. When your child was 19, 20, I would regret not having done it the way I could. At least my input has been as great as I could under the circumstances.''
Like her mother, Rachel has appeared in plays at her boarding school, but Rigg said she does not encourage her daughter to follow her footsteps, largely because she regrets not having continued her own formal education.
''If she wants to be an actress when she's been to university, got her degree, fine. Then she may decide. By telling her she's got to go to university, I'm not restricting, but possibly equipping her, if she enters the theatre, better.''
Next spring, balancing her career with her bargain with her daughter, Rigg will star in Dryden's All for Love in London, fitting in her twice-a-year tapings in Boston for the Mystery! introductions.
She'll turn up again in March for an hour-long television celebration marking the 20th season of Masterpiece Theatre, having starred as Lady Dedlock in its Bleak House several years back.
And from time to time, she'll do some writing.
''I write odd pieces for newspapers. I review books and that sort of thing. I don't think I'm terribly good at it. I think of all the arts, I admire the art of writing more than anything. I'd like to be good, to write well, but I don't.''
In 1983 Doubleday published No Stone Unturned, Rigg's humorous collection of disparaging theatre notices.
She also would like to direct.
''But I've got to go to school. One of these days possibly I'll go to the BBC and do one of their courses. I think it's such a responsibility, directing. So much is entrusted to you that you must know everything there is to know.''
If she ever does direct, she said with a laugh, ''I'd be jolly kind to the actors.''