Billie Eilish puts Manchester at centre of new 3D concert film

Singing superstar Billie Eilish and filmmaking giant James Cameron have teamed up to make a new 3D concert movie, documenting her shows in Manchester last year.

Cameron, of Titanic and Avatar fame, filmed Eilish over four nights at the Co-op Live venue during her Hit Me Hard And Soft world tour - the biggest of her career so far.

The outcome is both a thrilling sensory overload and unique love letter to her intense and adoring fans, who are often in tears.

Speaking to the BBC at the film's London premiere, Eilish said her fans in Manchester were "one of my favourite audiences ever... I fricking love Manchester".

Many of those fans travelled to the capital for Tuesday's blue-carpet premiere, hanging out of windows and lining balconies in Leicester Square for a glimpse of her.

"They didn't do that for me!" Cameron laughed when the fans erupted into deafening screams as she arrived.

For Eilish, 24, and Cameron, 71, the project is a unique one for both of them. The film came about after a suggestion by his wife, Suzy, who knows Eilish's mother, Maggie Baird, through their environmental activism.

"Little old James Cameron sent me an email literally saying 'would you be interested in making a movie of your concert in 3D?'" Eilish explained. "I had never even considered such a thing, it was such an amazing idea."

The film used new technology in the form of tiny 3D cameras to get up close and personal with Eilish on stage.

During her more energetic moments - she literally sprints from one corner to the other - a cameraman had the demanding job of trying to keep up with her.

"I said 'Billie, if he gets in your way, just mow him down - and she did!'" Cameron told the BBC.

Sharing the spotlight with Eilish are her fans, who are their own character in the film, Cameron said.

Even at the premiere, some had trouble speaking because they were so overwhelmed with emotions: "This is the happiest day of my life," exclaimed one.

Throughout the film, fans explain how Eilish has made them feel accepted, safe, seen and understood, especially during difficult times. She waved through a window at a group who have been camped out for hours to get to the front of her show.

She did the same at the premiere - taking time for photos and autographs with fans, and then a surprise re-appearance at the window of the cinema to more, deafening screams.

"I wanna be the artist that I would be a fan of," Eilish tells Cameron in the film, before showing her scratched-up hands from where they have grabbed at her.

While Cameron said he thinks Eilish tried to play it cool and not "fangirl" when she first met him, he wasn't nearly so calm, telling the BBC he was a "fanboy" from the get-go.

"Working with him was so magical in so many ways", Eilish said. "He really opened my eyes to seeing it as a film, and I'd been so used to doing it as a show with a live audience on a tour."