Good Posture is a comedy drama, written and directed by Dolly Wells, which explores female friendship. Star Emily Mortimer, who is Wells' best friend, talks to Georgia Humphreys about her experience on set and shares what she thinks needs to change in the film industry.

Frosty, frightening and intimidating perfectly describes Emily Mortimer's latest character.

It's the complete opposite to the London-born actress' real-life personality - and so playing reclusive author Julia Price, in new comedy drama Good Posture, was a really fun experience.

"I would love 1% of that character's frostiness," quips 47-year-old Mortimer, who is perhaps best known for HBO series, The Newsroom.

"You need it for life, and I don't have it, at all; I'm always trying to just ingratiate myself to people and make them like me."

Of course, playing someone so different to herself wasn't the only great thing about the film, which is set in current day Brooklyn, and follows the story of Lilian, a young woman who is placed into the care of family friend Julia after a break-up.

There was also the fact it was written and directed by Mortimer's best friend, Dolly Wells.

The pair, who were born four days apart, have known each other since childhood. Together they wrote and starred in Doll & Em, a Sky Atlantic comedy about two actors called - you guessed it - Doll and Em, who are best friends (it ran for two series from 2014).

Because of how close they are, the filming process for Good Posture, which was "really low budget", they had just 10 to 12 days to shoot, felt "very free, very collaborative", recalls Mortimer.

"Dolly's so un-authoritative, but had a really calm, quiet confidence, that I didn't expect," she confides.

"I mean, I didn't know what to expect, but then I suddenly saw her in this role, and she was amazing.

"In the centre of all this chaos and confusion, she was just able to breathe and not be panicking - often she is panicking in real life, and so am I."

She adds affectionately: "I think the atmosphere that Dolly created on this set was a very rare thing - and the best directors I have worked with have created that atmosphere - where you feel 'seen'.

"There's a sort of feeling, despite all of it, that there's all the time in the world to be you at that moment, and they're right there with you and they believe in you."

Both Lilian and Julia are fascinating, watchable characters. At the start of the feature, they have a passive-aggressive relationship, amusingly portrayed through notes they write to each other.

After Lilian suddenly decides to make a - admittedly unauthorised - documentary on Julia, to impress her ex-boyfriend and others, a rather surprising inter-generational friendship starts to develop.

Discussing the story, Mortimer reveals there were definitely elements of Julia that she could relate to - particularly the idea that both she, and Lilian, have always been defined by men.

"I think Dolly was making a really interesting point with that; you spend your life seeking the approval of men, and then you suddenly realise that actually you could get a quite exciting and fulfilling relationship from being friends with another woman, and that that might be more interesting, actually.

"And it doesn't have to be you're resorting to your women friends because you've been abandoned by a man or whatever..." she trails off.

You're choosing it, I suggest.

"Yeah, choosing it," she agrees. "I think our generation has definitely relied on the approval of men for our validation both as kind of sexual beings, but also in the workplace. You know, men have been the people giving the jobs and telling you you're good, as well as, 'you're sexy and charming', or whatever."

She continues: "What Doll was playing with so well, with the young girl kind of trope, coming into the house, threatening to destabilise your marriage, I totally relate to that feeling as well.

"Like, 'Oh god, they're a threat. There's this beautiful young thing who's going to be more attractive than I am' or whatever... The sort of culture of pitting women against each other and us buying into it, and it doesn't have to be like that."

Mother-of-two Mortimer currently lives in Brooklyn (Wells resides there too) with her husband, American actor and producer Alessandro Nivola.

She says she misses the UK "all the time", though admits she's relieved she's not having to deal with Brexit.

"I can feel, like second-hand, the stress of what's going on. I feel like nobody has a clue what to do."

Whatever the conversation topic, talking to Mortimer is really easy; she seems genuinely grounded and unreserved.

It's endearing hearing her discuss her love for Wells, as she explains how working with your best friend takes the pressure off, particularly on something you create together, like Doll & Em.

"As long as we can get into bed at the end of the night and gossip about what happened and chat about everything, it's OK.

"Of course, you don't want to feel like a tool and do something that's not good, and you're trying your best - but it ultimately doesn't matter. That's what it feels like."

Mortimer has had roles in a number of memorable movies since she started acting in the early Nineties, such as Match Point, Lovely & Amazing, and, most recently, Mary Poppins Returns.

She feels "much more hopeful" about the film industry at this point in her career, she says.

On the topic of what still needs to change, the star refers to sexuality and women, noting that "if you look a certain way you are attractive, and if you don't, you're not".

"That needs to change, and I think it is gradually, but it's not changing as much as everything," she elaborates.

"And I just feel like that... I think that's at the heart of real liberation for women. Because that's what it is for men; you don't have to look a certain way to be a sexy guy.

"Of course, there are stereotypes of male beauty too, and that has its own problems, and maybe increasingly so - as it changes for women the other way, there's more of stereotyping of male beauty.

"But I think that in film, I want to see women that don't look a certain way being treated as sexy, vibrant, vital women. And I think that that's going to feel so liberating."

Good Postures is in cinemas now.