The Brit plays a drug-addicted mum in the new film and admits it was a very different experience from filming James Bond movies, in which Harris plays action woman Eve Moneypenny.

"It was a massive change," she tells Access Hollywood Live. "When you're filming (Bond movie) Spectre and these big budget movies, you get these incredible palatial trailers, and instead we had one trailer for costume, for hair and for makeup, and there was one stool that all the actors shared."

And she can't believe the little film, directed by Barry Jenkins, is among the early Oscar frontrunners.

"I never thought that this movie would get all this kind of buzz, but it's fantastic," she gushes. "It's a movie I truly believe in, it has a wonderful message and I'm so pleased so many people are seeing it."

And Naomie admits she was so impressed with her young co-star Alex R. Hibbert, who plays her son in the film.

"He was only 11-years old and he'd never acted before," she explains. "He'd only come from his local drama club at school.

"It was amazing working with him. He was so professional and so talented; he actually taught me things. He had this amazing ability to be really light in between takes. He's, like, an incredible Michael Jackson impersonator, so he would sing and dance in between takes and keep the energy up on set."

Harris now hopes she'll return to the big screen as Bond's sidekick Moneypenny, but she has stopped speculating about who might be replacing Daniel Craig as 007 after upsetting her Mandela: Long Walk to Freedom co-star Idris Elba by talking about his credentials.

"It was me who started that rumour," she giggles. "He gets asked (about) that in every interview now because of me... It ages ago... It came out (in an interview) and he emailed me and said, 'Will you stop saying that'... It slipped out once."