KATE WINSLET’S powerful performance is already attracting frenzied Oscar speculation, but it is not the only striking aspect of Little Children.

The film, which showed at The Times BFI 50th London Film Festival yesterday, is the first mainstream Hollywood movie to depict a community’s victimisation of a convicted child sex offender.

Winslet, 31, said yesterday that it was “a really difficult subject” which she thought hard about before making the film.

Little Children’s plot centres on a passionate affair between a frustrated mother, played by Winslet, and a married man. But much of its atmosphere stems from the way that their Boston suburb responds to Ronnie, the “pervert” in their midst. It shows how parental protectiveness can escalate from dinner party gossip into vigilanteism.

“This man is extremely sad,” Winslet said. “Of course it’s a sinister subject matter but in a way Ronnie is almost anything but sinister. As an audience you feel incredible pity for him.”

The director, Todd Field, said that the character was meant to be “a living and breathing expression of the fear and anxiety and paranoia” that can corrode modern communities.

Field, whose last film, In the Bedroom, won the Satyajit Ray Award for a first feature at the festival in 2001, added that the nature of Ronnie’s crime was left out of the film, allowing the audience to draw their own conclusions about him.

“You can condemn him or you can pardon him. He’s not a villain and he’s not a saint,” he said. “The important thing was that, in a fable-like way, he would be a troll under the bridge. What then if the troll under the bridge had a mother? What if he could experience pain? But he is also a troll, so watch out.”

Everybody involved with the film emphasises that Little Children is not “a movie about a paedophile”. But its arrival marks the latest stage in the gradual erosion of the taboos surrounding the subject.

This year Hard Candy detailed a 14-year-old girl’s revenge on a predatory middle-aged man. Two prominent actors, Kevin Bacon and Brian Cox, have recently played paedophiles in low-profile films (The Woodsman and L.I.E. respectively), while Clint Eastwood’s Mystic River in 2003 touched on the issue.

Campaigners who work with child sex offenders believe that films can help to quench the hysteria around the subject and increase the possibility of rehabilitating them in society.

Helen Drewery, the manager of Circles of Support and Accountability, a government-backed volunteer organisation that works with sex offenders after their release from prison, said: “I think that there’s a reluctance to see both sides of the story with child sex offenders. It is treated like witchcraft in the seventeenth century.”

Read the film’s review at timesonline.co.uk/lff