Those who know Colman best for her portrayal of the late Queen Elizabeth in The Crown would be forgiven for thinking it was out of sorts. It's hard to imagine the Queen ever saying c---, and therefore a challenge to imagine Colman doing the same.

But it was more than that. Here was a well-respected woman who was fine with not just swearing, but using the "c" word in particular. A word that is controversial, to say the least. Indeed, it's one of the only two words that this masthead's style guide, like many others, chooses to blank out.

Still, despite its vulgarity, there is some nuance to the word's usage. Here in Australia, it can be used both with affection or with anger.

"We have the same relationship with it in the UK," Colman tells me over Zoom.

"You can say, 'Oh, he's a terrible old c---' and it's affectionate. Or, 'Soppy old c---' when you're giving someone a hug because they're emotional. Or it's done with rage, and it's got clout.

"But I love it because I think it's funny. I love the fact that it has so many uses and such power.

"I love that it's also a litmus test for who you're going to get on with. If you say the word and you can see people flinch, you know that, OK, we won't get on. People are funny about swearing. I love it and I do it quite regularly, I think."

Of course, like most celebrity interviews that go viral on the internet, it wasn't just a random remark that found itself living on our social media feeds. It was for Colman's new film, Wicked Little Letters, a true story that revolves so heavily around swear words, the film has had to make two trailers - one censored and one not.

It follows Edith Swan (Colman), a late-40s spinster who still lives a very restricted and chaste life with her parents in 1920s England. Next door lives Rose Gooding (Jessie Buckley), who is everything Edith is not. She swears like a sailor (and drinks like one, too), has a daughter everyone in town suspects was out of wedlock, and is, overall, loud and unruly.

Rose rejects everything society wants her to conform to, while Edith is the very example of what (unmarried) women should be. And yet, the two women - who are practically living on top of each other in the small confines of their Littlehampton homes - become unlikely friends.

"There's a lovely scene where Edith and Rose are walking along the beach together and starting to embark on a real friendship," Colman says.

"Rose is the only person who's ever seen that Edith is probably not having a happy life. And you think, 'Oh my god, they could both be really supportive of each other and happy and Edith could have been happy'.

"There was no opportunity [for Edith] to leave home. She couldn't earn her own money and you only really left if you were handed over to your husband. So that's why Rose was so amazing that she decided, 'F--- this. I'm going to do it my way'. And they could have had such a happy life if they remained friends."

But then the poison pen letters start to arrive.

"Dear Edith," the film's opening letter reads.

"You foxy ass old whore. You really are a tricksy old f---er and you're a sad stinky bitch."

It's worth remembering here that Wicked Little Letters is based on a true story and, yes, that's exactly what was written in the original letters. And, yes, people - including women - did swear in the 1920s.

But there is something a little off about the language used in the letter. No one swears like that, which is where the film's comedy comes in.

For (most of) the police in Littlehampton, this doesn't matter. They just assume the letter writer is Rose, because who else would use such vulgar language?

"It's sort of candid swearing, isn't it?" Colman says.

"Which I found so funny, that someone had heard these words, and they're throwing them in this sort of pot, and seeing what will happen. And that doesn't always work successfully. But it's very funny."

Set in the 1920s, Wicked Little Letters is the sort of film that feels too good to be true - in juxtaposition to what we think we know about women in post-World War I Britain.

But it's not such an unusual story. Poison pen letters - in many ways the original trolling that we see on social media today - were an unusual crime wave of the early 20th century. Anonymity allowed the freedom to write these libellous letters that caused such shock to their recipients.

There is a difference when it comes to the letters of Littlehampton - audiences will have to watch the film to find out what. But at the time, the scandal captivated the town; everyone had an opinion.

And when it came to the police, that opinion would lead to a wrongful conviction. Aside from "woman police officer" Gladys Moss - as she is referred to in the film - the police are convinced it's Rose. The film is as much about Gladys (played by Anjana Vasan) trying to convince her male counterparts that they have arrested the wrong woman, as the tension between Rose and Edith.

In many ways, this story arc is the film's most believable - a woman struggling for the equal opportunity with her male counterparts.

But the further challenge must have been making the story - one that, while true, is bizarre and easy to question - feel authentic for a 21^st century audience. No one was more aware of this than director Thea Sharrock.

Still, when she was first handed the script by Jonny Sweet, she had no idea it was a true story, only that it shone off the page.

"When I discovered that it was based on a true story, I literally couldn't believe it," Sharrock says.

"But now, on the other hand, I just think it's so British. It's so uptight, and about release which makes sense, but it's still, it's wild, isn't it? It's an extraordinary story about a pretty extraordinary woman at the centre of it."

Yet from society's point of view, someone like Edith has been written off as being pretty average, with - like many women of the time - no power, no agency, and no say in anything. Nothing exciting has really happened to her - as far as the audience is aware - and as these letters gain traction, she's thrust into the limelight. The effect is like peeling back her layers.

For what seems like the first time, she is seen. Not for the entirety of who she is, but still, this is her 15 minutes of fame and her eyes glisten with delight.

"When you have Olivia Colman in the centre of all of that, not only is she just remarkable and she's so accessible as an actress, she's so easy to fall in love with even when she's playing a character like this," Sharrock says.

"She has a way of understanding and clicking into what it is that makes her character tick - understanding whatever their complexities are, and what we find difficult about somebody. She has a way of just getting in and understanding it. She doesn't question it. She doesn't judge it. And that's where the depth of the character can come from."

It's a depth co-star Jessie Buckley shares, through the character of Rose. Despite everything, Wicked Little Letters isn't just about two women against each other for the sake of it. It's far more nuanced than that.

"Edith certainly is getting something out of her sudden ascendancy and Rose being thrown into those depths of despair was part of what she took pleasure in," Sharrock says.

"But without question, she didn't anticipate that, because I don't think she saw it coming. And that's where we get the scene where Edith is saying to Rose, 'I wish it wasn't you'."