Between sips of hot tea and ladylike bites of finger sandwiches, good-girl Hayley Mills is praising the joys of being bad.
 
"I just played a very, very nasty character on stage in London," she says, crinkling her famous pug nose, of her 14-month stint in the psychological thriller Dead Guilty.
 
"She was a sort of Misery-type character. It was a very interesting experience -- and difficult to find the character (within me)," says the actress, smiling, "but I learned a lot. I don't always just want to play it `good.'"
 
But good is how we usually think of the veteran of six perky Disney flicks.
 
At 51, Mills still possesses the haloed blond locks and cherubic face of her goody-goody Pollyanna persona in the ever upbeat 1960 Disney film (for which she won a special Oscar) .
 
Playing mischievous -- but endearing -- characters in The Parent Trap, The Chalk Garden and The Trouble With Angels, the teen actress became an enduring institution in the way of Patty Duke and Gidget.
 
"People see my face and remember their childhood," says Mills, who has spent the second half of her career veering away from that image.
 
"The truth is, people don't really change that much," she says, "we're all just a bit older, a bit fatter, a bit thinner, a few more lines..."
 
In real life, Mills may resemble those happy-go-lucky roles more than she dares admit.
 
But for North American audiences, who have missed her varied theatre turns the last few decades in Britian, Australia and even Russia, it's time for a re-introduction to Mills, the actress.
 
In town for a two-week run of The King And I (at the Hummingbird Centre For The Performing Arts starting July 23), Mills is prim governess Mrs. Anna opposite the stubborn King (Vee Talmadge).
 
While not as darkly challenging as her Dead Guilty role, Mills is exercising new chops in her first big-budget ($5.5 million American) musical.
 
Originating the role in the revival that toured Australia in 1991, "I had first said, `No, no, no (to the part)!'" says Mills, who hadn't carried a tune on stage since 1970 and is required to belt out five doozies in King. "I wasn't sure my voice would hold up."
 
In this version of the Tony Award-winning Rodgers and Hammerstein tale, the focus is more on Hayley's Anna than any that have come before.
 
"It was their original intention to concentrate on the relationship, the conflict, between (the King and Anna)," says Mills of the playwrights.
 
"When Yul Brenner did it, it was so (focused) on the King because he did it ad infinitum for nearly 30 years, with many different Mrs. Annas coming and going," she says. "He had such a dominating influence on stage, it seemed to be a show all about the King, and it's much more complicated than that."
 
Taking this role, she says, was "a big risk ... and one of the most rewarding" in her career.
 
But coming from the sturdy stage stock of Oscar-winning dad Sir John Mills (Ryan's Daughter), such aspirations are in her blood.
 
"The the-ah-tuh is like home to me," she says, in a well-bred, British staccato. "I never had to worry about image so much there."
 
Ironically, her early screen image is not only alive, but thriving, with Disney's recent video releases of her films.
 
"My generation grew up with it, and now their children are, which is wonderful," she says, noting that many of her new young fans are the ones waiting at the stage door each night for autographs.
 
But it was that early squeaky-clean screen image, she says, that hindered her growth as an actress -- and a person.
 
"It was difficult to free myself from the kind of roles I had played," she says. "For a while it did get in the way of an otherwise natural development."
 
One early manifestation was the eating disorder bulimia, which lasted until she had her first child, Crispian, now 24 (she also has a second son, Jason, 20).
 
"I look at women today trying to be unnaturally thin and not accepting their own natural beauty," she says, shaking her mane of hair. "They are not enjoying their youth and the moment they are living."
 
Kicking the low self-esteem bad habit was "all part of growing up and getting a bit of wisdom," she says.
 
Much of her own wisdom has come from studying Eastern religions, which she first "encountered" 15 years ago.
 
"It was at a turning point in my life," explains the actress, a practising vegetarian and meditator.
 
"Without a spiritual motivation ... seeing life through spiritual eyes, having spiritual principles on which to build your life, I think life is exceedingly difficult.
 
"It helped me get back to my own sense of myself as a spiritual being on a material journey rather than a material being on a spiritual journey."
 
And while that journey includes exploring dark, unchartered territories in her work, the ebullient Mills still prefers the kind of "life-enhancing" roles, like Mrs. Anna, that give good karmic return "on a personal level."
 
"In the beginning of my career, quite honestly, I didn't know what sort of roles I should be looking for," she says, "because I hadn't developed sufficiently within myself. To find out what kind of a person you are -- that takes a lifetime.
 
"Happily, you never really quite get to the bottom of it."
 

 
THE HAYLEY MILLS FILE
 
ACTING LINEAGE: Dad is Sir John Mills (Ryan's Daughter), sister is Juliet Mills (Nanny And The Professor), mom is author Mary Hayley Bell (Whistle Down The Wind).
 
FILM DEBUT: In Tiger Bay (1958) opposite Horst Buchholz and her dad.
 
SINGING SENSATION: The tune she sang for The Parent Trap in 1961, titled Let's Get Together, was a top-10 hit on the charts.
 
HER BAD-GIRL BREAKTHROUGH: A nude scene from behind in the film The Family Way (1967). "It caused such a ruckus ... how silly," she says.