Image copyright Getty Images Image caption Felicity Jones and Eddie Redmayne at the Toronto Film Festival

Eddie Redmayne has described the "absolutely wonderful" experience of being reunited with Felicity Jones on screen.

The pair first teamed up on 2014's The Theory of Everything which earned Redmayne an Oscar.

Now they're returning with The Aeronauts, which premiered in Toronto on Sunday.

"When someone suggested it, I thought oh yes, that would be amazing," Redmayne said of their reunion.

"It was absolutely wonderful. It was one of those things where we'd had the most intense and extraordinary experience making The Theory of Everything, and when we were offered this script it was that slight nervousness of 'Do we go back?'

"But we enjoyed that experience so much, so we called each other up and I was like, 'I'll do it if you do it'. And I'm so thrilled we did because it was a ride."

Set in 1862, The Aeronauts follows balloonist Amelia Wren and meteorologist James Glaisher, whose goal is to fly higher than anyone in history.

But they face both physical and emotional challenges as the altitude increases, and the pair eventually have to fight for survival as the air thins.

Image copyright TIFF Image caption The Aeronauts premiered in Toronto on Sunday

The film is directed by Tom Harper and written by Jack Thorne, who is well known for scripting the Harry Potter play.

"For me it's a film about wonder," Redmayne told BBC News. "And we're in a world in which, and I'm a massive culprit of it, we spend so much time looking at our phones and looking down, and for me the film is about looking up, so that's what attracted me to it."

Jones said the pair have a good working relationship because of their similar approach to filmmaking.

"We're such great friends and we're both very meticulous, we push each other, it can be quite an intense process working together," she explained.

"We're very similar in that we don't stop until we get something that we think is good. We'll keep pushing for takes, so it was a wonderful experience to work with someone who is as emphatic and determined as oneself."

She continued: "We both said yes together, we were sent the scripts separately, and the fact they're both such brilliant characters, that's what clinched it. I think had one character not been so good the other person may not have wanted to take part, but there were was so much rich stuff for both of us, so it was a mutual agreement."

Image copyright Getty Images Image caption Jones said she was desperate to return to some action since working on Rogue One

Jones added the film was an opportunity to return to the style of role she hasn't done since her appearance in 2016's Rogue One: A Star Wars Story.

"I was desperate to do some action, having done Rogue One a few years ago, and there's this wonderful climb that Amelia Wren has at the end of the film, and that's what clinched it for me, just being back doing an action film."

Critics have welcomed Jones and Redmayne's reunion, although the film has received mixed reviews overall.

"The script unfortunately settles for the bare minimum to define James and Amelia, and steadily loses air when it reaches for melodramatic cliches," wrote Tomris Laffly in Variety.

"Tedious and increasingly unwelcome flashbacks feel exasperating as they continually interrupt the balloon's graceful yet perilous glide over London and undercut the brainy tête-à-tête between the leads."

Eric Kohn of IndieWire added: "The Aeronauts throws historical accuracy to the wind, but at least does justice to the thrill of early flight, using new technology to enhance an old-fashioned survival story.

"There's enough potential with the balloon's feats to justify an entire feature-length experience set within its basket, but The Aeronauts constantly interrupts the journey to shoehorn random tangents on the ground, and busies up the drama with underdeveloped side characters."

The Aeronauts is set to be released in cinemas for a short window before Amazon Studios makes it available on its streaming service.