But seriously, folks: Brenda Blethyn in Introducing the Dwights, opening this week in New York (Photo: Warner Independent Pictures)

Brenda Blethyn wasn't totally sure how it happened, or that it was even happening at all. Or even why writer Keith Thompson wrote the part of Introducing the Dwights' single mom/cafeteria cook/comedienne Jean Dwight with her in mind. There was that Mike Leigh film she did a while back -- not the Oscar-nominated, Cannes-winning Secret and Lies, but the modest BBC project Grown-Ups 16 years before that. Perhaps it was all those variety acts she used to sneak peeks at in their gigs near her (and Thompson's) hometown in Kent, England.

"I was fascinated by them," Blethyn told me last week while promoting Dwights (a k a Clubland, its better-known international title), which opens this week in New York. "You've got dancing dogs; you've got a lady with a load of birds performing and jugglers and ventriloquists. It all seems kind of sad and seedy, but it didn't mean the acts weren't good. They were all taken dead seriously by the performers, who did their absolute best, all hoping to get that one phone call that might launch them to stardom, and probably none of them ever getting it. But that flame of optimism still burns -- as it does with Jean after 25 years. All of that came into play."

In that 25-year interim, Blethyn's high-strung entertainer raised two boys by herself in a Sydney suburb, all the while keeping an eye on the club circuit to which she planned an eventual return. In a hitch of convenient dramatic timing, her comeback coincides with her oldest son's first serious romance and youngest, disabled son's fledgling independence. Out of nowhere, Jean faces the shocking prospect of being alone. "I think there's a special dynamic between mother and son as opposed to mother and daughter," she said. "Or father/son, father/daughter. When a daughter marries, she stays within the bosom of the family. When a son marries, he is usually adopted by the wife's family. If they have children, it will be the wife's mother who's called on first, I suspect. Jean just feels like her position has been usurped. She adores the those boys and is going to miss them."

And though Blethyn acknowledged relating to Jean's ebullient optimism and creative passion, she said that was where the similarities between her and Thompson's reluctant heroine end. While not especially wicked, Jean's possessiveness over strapping young Tim (Khan Chittenden) does evoke a raw, meandering sort of awful that both affirms and betrays what we expect of more overbearing movie mothers ("Did you have a good night?" she asks Tim after coaxing him home. "No," he says. "Good," she laughs, embracing him). Her guarding of Mark (Richard Wilson, all spunk and affected cerebral palsy) slips into neurosis as he actually braves the front yard and -- in a sequence of prolonged indie heart-pinching -- an ice rink.

The consequences waiting for the brothers and Tim's nubile paramour Jill (a splendid Emma Booth) are predictable, but Blethyn, ever the performer her bereft Jean once strove to become, nails a near-perfect ratio of alienation and sympathy. As opposed to loving to hate her, viewers hate to not love her -- maybe because they've chugged this formula before and know about its smooth finish.

Or, all cynicism aside, maybe it's because they relate. At least Blethyn did. "She hasn't been there before!" she told me. "We all do things that we regret doing. We all behave badly at times in our lives, and every single one of us says things we shouldn't, and regrets them and carries on doing it. There's no censor. That goes out the window when you get upset or angry. But what I'm fascinated by and always have been is embarrassment. There's a lot of embarrassment in this film; Jean's embarrassment is excruciating. It's kind of funny on one hand and excruciatingly painful on the other, and I found the challenge of that as an actor appealing. And I also knew that for part of the film she would be unsympathetic. That's a challenge I find a joy to play, to be honest with you. But I forgive her."