Onata April: The What Maisie Knew child star outshines Julianne Moore and Steve Coogan

Onata Aprile, the acclaimed star of What Maisie Knew, was only six when shooting started. Kaleem Aftab meets a precocious talent

The praise Onata Aprile is receiving for her performance in What Maisie Knew would please a veteran actor

The praise Onata Aprile is receiving for her performance in What Maisie Knew would please a veteran actor let alone by a girl who was just six years old when the cameras rolled on the movie adaptation of Henry James' 1897 novel.

Laurence Phelan, reviewing in The Independent, described her performance as “beautifully and very naturally played”. Justin Chang in Variety weighed in with “Aprile is remarkable as Maisie and manages to convey in every close-up the painful, premature knowledge described by the title”. Anna Smith in Empire said, “performances are strong and Aprile is a remarkable young talent”. Not since a seven-year-old Dakota Fanning exploded into the public consciousness in 2001's I Am Sam has one so young received so much praise.

Aprile is the eponymous character in the tale of a young girl used as a pawn in a difficult divorce. It's some feat that she manages to outshine the performances of both Julianne Moore and Steve Coogan, who play her parents. Both claim to want guardianship of Maisie after a messy divorce but try to palm their daughter off to each other whenever the difficulties of parenthood get in the way of their own lives. Maisie spends more time with the new partners of her parents, played by Swedish star Alexander Skarsgard and Scottish actress Joanna Vanderham.

Her relationship with Skarsgard is pivotal. When I meet Aprile, she is clinging to the True Blood star. The precocious talent shows she has an eye for stardom by wanting to be interviewed on a day of interviews that also features Skarsgard and the film's directors Scott McGhee and David Siegel. Yet upon meeting her it becomes apparent just how remarkable her performance is, as she seems far more boisterous and independent then the character she plays. She delivers short, monosyllabic answers that one would suspect from one so young.

She says what she remembers about being on set is “Alex would carry me by his arms.” Her co-star would amuse her between takes of the many scenes that they acted-in together by swinging her around the room.

Skarsgard is as praising of his young co-star as the reviewers, admitting that the film would have been a disaster if the wrong girl had been cast. “It was all about finding the right girl,” says the 37-year-old. She's in every scene. It doesn't matter how good the script is, how great the directors are, or the other actors, if you don't fall in love with the girl then you don't have a film.“

What Maisie Knew is told from the child's perspective and Skarsgard said he had to make sure that they had a believable connection – “finding a kid that had that raw quality, who wasn't a Hollywood starlet, someone who is real”.

Aprile, who recently turned eight, says, about playing Maisie, “I liked playing her a lot. It was a lot of fun”. As for any preparation, she said: “This is the only time I have seen Alex in a film. We did a little bit.” Two weeks before shooting she and Skarsgard met and they played a bit and familiarised themselves with each other, so that there was a natural chemistry on set.

Given her stunning performance, Skarsgard could get a job as a child acting coach should he ever hit a roadblock on his own stellar career. Aprile wanders in and out as I chat to Skarsgard, answering questions when she feels like it and then disappearing when she is bored. Skarsgard sat with Aprile when they watched the premiere. The actor asks Aprile if she has ever seen herself on screen before. The young actress has had roles in an episode of Law and Order and has had parts in Nick Cassavetes's Yellow, and The History of Future Folk, a sci-fi adventure about the origins of an alien bluegrass band. She says that this time was the first time she was allowed to see her own work.

Aprile is taken everywhere and mentored by her actor-mother Valentine, who appears with her daughter in the short film Twist. Valentine's Twitter account reveals that she has just finished making a film Babysitter and she has a Facebook page promoting both their careers.

The directors, Scott McGehee and David Siegel, who previously made The Deep End with Tilda Swinton, remark that Aprile's mum is far from the stereotype of the pushy stage mother.

Key for them in getting a performance from Aprile was building up her trust in both them and the actors. They had heard some horror stories before about how film-makers try to coax performances from young stars, including a tale told to them by an assistant director who had spent the whole shoot of a movie building a relationship with a child star. The motivation for doing so was that when the director needed an emotional performance from the child she told the kid that her parents had left her and would never come back. The directors lament, “she built up this bond of trust for this one moment – and was telling us this proudly.”

They gave Aprile toys on set to amuse her. What they saw as a potential problem was having the tiny Aprile being intimidated by having to act alongside a 6ft 4in actor. Luckily, they say: “Alex is so great with children that it was never an issue. There is something about this young girl being so small, and putting the two of them together and in a single frame was remarkable. ”

“The whole reason we got involved in the project was the challenge of telling the story,” says Siegel. “We needed a child that could convey that experience and to do that we were lucky to find an actress like Aprile. When we cut the film we were surprised to see how much we could rely on her performance. She is so good in the close-up. We were really lucky.” It was a huge risk to rest a whole movie on a child's shoulders but the critical reaction has proved that they were right to do so.

So what next for the young actress? Aprile is currently a student at PS3 school in Manhattan. She has taken no acting roles since appearing in What Maisie Knew, suggesting that Valentine is keeping her daughter's feet firmly on the ground.

'What Maisie Knew' is out now