In this photo from his movie Nanny McPhee, Colin Firth is up to his arms in babies.

LOS ANGELES -- If Colin Firth genuinely had tried to exploit his 1995 rocket to fame as Mr. Darcy, he would not have spent the past decade being eccentric in his roles.

Such as co-starring, opposite Kevin Bacon, as the smoldering, sexually conflicted singer-comedian in Toronto filmmaker Atom Egoyan's controversial Where The Truth Lies.

Or following that adult film noir thriller with the current children's comedy, Nanny McPhee. In this whimsical delight, Firth does slapstick as the hapless Victorian widower who has lost control of his seven unruly children.

This is hardly the master plan of an actor trying to promote himself as a leading man after the BBC version of Jane Austen's Pride And Prejudice turned him into a star and wired him into pop culture as a romantic icon.

"I think it is folly to do that," the 45-year-old English aristocrat tells the Toronto Sun in a one-on-one interview after shilling for Nanny McPhee during a press conference. "Because you can't control any of it, in that way.

"We can choose our motivations. We can choose what we want to explore. But you can't dictate the outcome. You can't write a script for a career's trajectory, and the success thereof. You just can't. I think that anyone who tries to structure things with that in mind is on a fool's errand. It comes unstuck very quickly, and there's not fun in it, either."

But on Nanny McPhee, which was written for the screen by Firth's co-star Emma Thompson (who also plays the title character with glee), there was tons of fun.

"This was a nauseatingly happy shoot," Firth says of shooting on location in Buckinghamshire and at England's famed Pinewood Studios near London.

"You know, people who came to the set, they could really be forgiven for loathing all of us! It was just this daily joyous kind of lovefest. And no one really wants to hear about that happening to someone else."

The fun was mostly non-stop except, of course, for dealing with that damned donkey, a stubborn ass of an animal who refused to do director Kirk Jones' bidding when the humans dressed up a barnyard of animals in people's clothes for a climactic scene of hijinks. "I'm sure Kirk is still having nightmares about the donkey," Firth says with a chuckle.

That Firth is laughing at all today is refreshing. The last time we sat down for an interview -- at the Toronto filmfest in September when Where The Truth Lies made its North American debut -- Firth was staggered with fatigue.

He had flown in from Morocco, where he had been shooting an action-adventure movie. The media that day, including your Sun representative, were all fest-tired, too.

"It makes you realize," Firth says, recalling the Toronto experience, "that almost everything you read about movies is written by strung-out people about strung-out people. Everybody's jetlagged and wired and over caffeinated." He finds that odd and amusing.

Life on the Nanny McPhee trail is laid back, California style, however. Firth is sanguine and smiling. And willing to try to put into words what he feels so strongly in his heart: That the point of all of this is simple; it is about storytelling.

"My love of storytelling began as a child, which I sort of think is true of most of us," he tells the press conference. "Mine was possibly more obsessive than others, to the extent that I had to pursue it as a profession.

"I think there is something about telling stories for children which takes you back to that root. I am a storyteller. I am a professional fantasist. That's what I do as an actor."

On Nanny McPhee, he says, "I think there was something liberating about not hiding behind the kind of veneer of sophistication and irony that telling stories for adults tends to involve. We're trying to delight children. Scare them. Make them laugh. Whatever.

"It's just a much less self-regarding process and it brings you back to the joy of being spellbound by the stories you were told as a child."