TWENTY FIVE years ago, Kirsty Mitchell was a beauty queen, crowned Miss Scotland. Now, the woman who grew up in a one-bed flat on a Possilpark council estate is conquering television screens around the world as the ultimate warrior queen, Boudica, leader of the Iceni tribe of Celts.

On promotional material for the History Channel’s new docu-drama show, Barbarians Rising, Mitchell glowers out from underneath smudged blue battle make-up. This is no graceful catwalk queen. Rather, Boudica is a wild-eyed wronged woman ruler intent on revenge, who, following her own flogging and the rape of her daughters by the Romans, brings together the Celtic tribes of ancient Britain to rise up against the Empire. Boudica is one of the key faces in a lavish series, screened on both sides of the Atlantic, that charts the way, across Europe, Roman rule was challenged, declaring, in its tagline, “Rome didn’t fall in a day'.

Attila the Hun, Spartacus, and Alaric, king of the Visigoths, are among the other rebels. The series began on Wednesday with the story of Hannibal, ruler of Carthage who challenged Rome by famously invading Italy over the Alps with battle elephants in tow.

So brutal are some of Mitchell’s scenes, that she says her 14-year-old nephew has not been able to watch it. “He got as far as the flogging,” she says, “and then he was like, ‘Okay, I’m out'.” For her the role was exhausting, its biggest challenge not the physical effort of the many fighting scenes, but “keeping up that level of heightened emotion for that length of time”. Though, for the past few decades, she has been a busy jobbing actor, notching up roles in Small Faces, Monarch of the Glen The Royal Today, River City, she has, she says, played nothing like it before. “You don’t get to play roles like that. I’ve played roles on stage that involve a lot of emotional turmoil but I’ve never presented anything like that on screen. It was a massive role to take on – emotionally, physically and even as far as dialogue was concerned. But I wasn’t scared of it.”

The Boudica of this series is a tough and savage fighter; a killer of men and women. Her slash and burn campaign on the Roman settlements, which would leave over 70,000 dead, many of them civilians, was by all accounts merciless. But, Mitchell notes, the series questions the idea that these "Barbarians" were “barbaric”. “The Celts,” she says, “were just responding to Romanic behaviour. These people came in and invaded our homes and wanted to destroy our way of life - our legacies and druid ritual, they wanted to destroy everything we had, our history, so we responded to their behaviour. Fire with fire. I find it very intriguing now that it’s called barbaric behaviour.”

What marks Barbarians Rising out as a little different from many historical epics is that it presents itself not as a straightforward drama, but as docudrama, and features talking heads sections, in which historians explain the backdrop of the story.

In many ways Boudica is the face of the series. It’s she that is positioned centrally on the publicity material: her fierce, battle-ready gaze - every inch a crazed-looking Katniss Everdean from Hunger Games meets William Wallace. It’s an iconic image. Already, says Mitchell, a number of people have told her they are going to dress up as Boudica for Halloween.

In fact, we know little about what Boudica would have looked like, accounts of her coming from only two sources, both Roman propagandists. “She is written as this really tall red-head with a deep voice, and who knows, the Romans might have amplified that,” says Mitchell.

That Boudica should have emerged as one of the key figures in the way this series has been promoted should be no surprise. Women heroines are, following the success of the Hunger Games series, Star Wars: The Force Awakens, and even superhero films like Suicide Squad, the flavour of the moment.

“I think,” says Mitchell, “things have changed quite dramatically in the past few years. There has been a massive demand for these kind of stories and roles. Women want to see the power and emotions of what women have to go through and what they have to deal with in life. It’s great to be able to portray these women as well as weak women, because we have a whole variety of people out there.“

As soon as she read the script Mitchell decided, with a warrior-like intent, she had to play Boudica. “I basically walked in and told the director this is my role. It was mine, I had to have it. I was desperate to do it.” Before playing the role, she had a vague idea of the story of this queen of the Iceni people, but as soon as she was cast, she researched the role fanatically. Because the series is factual, Mitchell says she was “insane in my research", adding: "When I do a medical drama I’m up till 4am because I’m reading about the operation I’m going to do and, before I know it, it's like I’m studying medicine.”

Mitchell acknowledges that she is a fighter by nature herself: and that this was partly what took her from a council estate upbringing to an actor’s life now in Los Angeles. “If you look at where I started, I trained as a ballet dancer and where I came from there wasn’t a lot of kids that did that. Then I got a grant, I had to fight for my grant to go to ballet school. You go there and you’re fighting for your place there. I feel like I’ve constantly fought for where I’ve wanted to go, and then when I’ve wanted to act I didn’t get handed it on a plate. I fought and worked hard for every rung of the ladder I stepped."

Four years in LA, plus a string of sessions with speech therapists, have meant that now, as she chats, her accent seems to modulate, between American, Glaswegian, RP English and even a twang of Ulster. It’s a testimony to her discipline and determination that at one point she did two hours voice-work a day to change her vowel sounds. “I’m posh now,” she jokes. “My family call me the posh bird. I wanted to change my vowel sounds because when I walked into auditions I didn’t want to be stressing about getting it right. I just wanted it to be second nature. So I studied and I studied.”

In Barbarian’s Rising Boudica’s accent is unlocateable, a kind of wandering English-speaking voice that seems to take a tour of the isles. What you hear on screen though is nothing like Mitchell’s own voice. Rather, as she points out: "It’s octaves lower. My friends were saying, ‘Are you dubbed?’ Basically I found the voice that I felt was the power accent, the power voice, and used that.”

What’s remarkable too is that she is getting some of her biggest roles now, as she enters her early forties. At 42 years old, she is as busy as she has ever been. Mitchell was also in New Blood, broadcast earlier this summer on BBC1, in which she played an assassin. “She’s a killer of a different sort,” she says. “It must be my killing spree year.” It is only recently that she has hit the age, she notes, where she has become cast-able as “the mother” – and this has opened up a whole range of roles, like Boudica herself.

Mitchell’s is not the first screen portrayal of Boudica, nor will it be the last. Over the past decade many directors and producers, from Mel Gibson to Stephen Spielberg, have mooted bringing Boudica to the big screen. She has a great deal in common with some of the most popular heroes of historical drama – Braveheart’s William Wallace, Robin Hood, Spartacus – in that she is an outsider, at odds with the powers of the time. She is, as commentators were quick to point out when Mel Gibson was involved in a Boudica project, a kind of “Braveheart with a bra”.

The William Wallace connection is one that is not lost on Mitchell. “She’s rebelling,” she says. “She’s a rebellious leader. And she’s a freedom fighter. So it is the same concept as the Braveheart movie. And we love that concept.”

Barbarians Rising is on The History Channel on Wednesdays, 10pm