Kristin Scott Thomas and Sharon Horgan run a choir on an army base in new film Military Wives. Laura Harding sits down with the two stars and director Peter Cattaneo to talk about bringing the real story to life.

It was almost 10 years ago that the nation fell in love with a group of military wives, who found solace singing in a choir together while their partners were away in Afghanistan.

The three-part BBC documentary brought together wives from five UK barracks under the guidance of Gareth Malone, culminating in a performance at the Festival of Remembrance at London's Royal Albert Hall.

Now their moving story is getting the big screen treatment, but with Malone's role devolved to two of the wives running the group, played by Kristin Scott Thomas and Sharon Horgan, and with The Full Monty director Peter Cattaneo at the helm.

"I love telling the story about people we don't usually hear about," Scott Thomas says, "about families, about people who have to go through such anxiety and tension and waiting.

"I just thought there was a really interesting group of people that I hadn't actually seen a film about before."

Horgan, who is best known for writing and starring in Catastrophe, nods. "Yeah I think that's really true. I didn't know about that world at all so it was something about telling a story that hadn't been told before, not a film version, and because Kristin was doing it I was really excited to work with her.

"And Peter seems to know what he's doing so I knew we were in safe hands. I knew he wouldn't go schlocky on it."

She laughs. "He wouldn't make it too treacly."

Indeed Cattaneo sees the connections between this film and his 1997 hit about a group of unemployed steelworkers who form a male striptease act.

"Kind of to the point, is that a good thing or a bad thing?" he admits.

"But when I got a bit more involved and it felt like it rang true. I met a lot of the women and I was hearing a lot of these stories and these details and it felt like the film had its own inner life.

"It wasn't just something that was constructed for the outside, so I thought if I follow the truth and get these details into the movie, it's going to resonate."

For 59-year-old Four Weddings And A Funeral star Scott Thomas, who grew up in a military family, she also wanted to shine a light on the women left behind, who have been largely ignored by war films.

"It's a film about women, for women, all of the above, hopefully if this film is a success people will start to make more films with women's stories that don't have a man in the middle."

"I think it's quite a brave thing to do," 49-year-old Horgan adds, "because if you've got a war story there is instant drama, there's guns and there's bombs and there's bravery and there's all those things, whereas this is a quieter story.

"There's lots of bravery in it and an amazing story but the dramatisation of that might not seem immediately 'let's do it!' but it works."

It was for that reason that making the representation of these women's lives as accurate as possible was of utmost importance.

"We were very conscious of that," Scott Thomas says, "and very relieved to meet ladies and at the premiere families who reassured us they had done a god job in making it look like it actually happened."

Horgan nods.

"Even the little details, for them that really resonated, That is what their kitchens look like," she says, "and that is how the women talk together and it's not all about how awful they are feeling, it's about having a laugh."

They filmed on a real military base and real military families feature in some of the scenes.

"Getting in and out every day was a bit of a number," Cattaneo laughs, "and we did do some drone shots at the beginning but we couldn't get too close with the drone.

"But really the difference was punctuality and the difference between film unit punctuality and military unit punctuality."

He laughs. "There is quite a bit gap."

And while Malone doesn't feature in the film, he did serve as a consultant, providing valuable help to the director.

"I sent him a few drafts of the script (by Rosanne Flynn and Rachel Tunnard) and he would send me a few really smart notes.

"He's hung out with the wives a lot so he knows the kind of spirit of their lives and what sort of characters they are.

"But the best thing was the little details about being in the choir. We had military advisers but he was really the choir adviser.

"There is a scene in a tunnel which was slightly different in the script at one stage.

"They were singing outside and I had this idea they were going to kind of stand on a hillside and shout and express themselves and he was like, 'I like that scene but if I was out with a choir in the Yorkshire Dales I would find a cave or a railway tunnel or something because of the acoustics' so we were like, 'Good idea, thank you very much Gareth!'"

But without Malone's character, much of the pressure of sounding great while singing fell on Scott Thomas and Horgan.

So where does singing rank on the list of scary things to be asked to do?

"Pretty high," Horgan confesses. "Dancing would be the highest, right? Please no. Never ever ever, don't even ask me to walk in time to something or click my fingers."

"Or talking and dancing," Scott Thomas chimes in. "Have you ever had to do that? It's impossible. Singing? Next. It was pretty frightening."

"Until we realised that we were all scared," Horgan says, "and all in it together and when we put all the voices together it sounded fine, it sounded quite good.

"Initially we had a tiny bit of singing practice all together and I remember listening out for the really great voices and hearing where they were.

"That was good, because I thought, 'It's going to sound fine, we've got her.'"

Military Wives is out now in UK cinemas.