‘Prime Suspect’ star Stefanie Martini has come a long way

She may be on the sweet side of the law these days, but actress Stefanie Martini used to be a rebel. The British performer finds herself in the spiffy uniform of police detective Jane Tennison on the PBS rewind of “Prime Suspect.”

Martini plays the young Tennison, a role made famous by Helen Mirren when she starred on the series for seven seasons.

But this version, premiering Sunday, takes us back to the ’70s when Tennison was a rookie and coping with a gang of ‘good ol’ boys’ in the squad room.

“The thing that was so shocking to me was the every-day sexism that was just accepted,” says Martini, seated in a noisy meeting room here.

“There were just little bits where: ‘Can you make the tea?’ ‘Can you wash my plate?’ While he’s checking out a bum. No one even comments about it. They’re called PLONKS, people of little or no knowledge,” she says. “In my generation that would never happen. It’s good to see how far we’ve come.”

It’s good to see how far she’s come. Martini landed the coveted role only six months after she’d finished drama school at the Royal Academy of Dramatic Arts. “I’d done enough stuff by that point that I could feel a bit more secure in what I was doing and a bit more like I kind of knew how it works, how being on a set works. And I think it came at a good time for me, because I think if it had been any earlier I would’ve been so frightened.”

Still she had to audition three times and wait for five months for a decision to be handed down. During the long wait, she was convinced she’d lost the role. “I told myself I hadn’t got it — already in my head — so I wasn’t bed-bound crying for two weeks. I just tried to keep grounded about it, and not get too attached. When I found out I did get it, I was overjoyed. And then afterward, I couldn’t quite believe it was actually happening, and I was terrified.”

Deciding to become an actress was a giant step in the first place for Martini, who describes herself as a naughty nerd in high school. “I was kind of naughty, but in a quite silly way. When I was a teenager I was a Goth. I know it’s ridiculous. I can’t imagine it now, but I was a rebel in my own way.

“Everything was great in my life. I had nothing to rebel against. But I was into all kinds of teenage angst. I’d wear ridiculous clothes, fishnet tights on my arms, loads of bangles and rings, red hair,” she says patting the top of her ash blonde hair.

“I was a big nerd and would never do anything harmful to anyone. I wasn’t naughty in that way, but I had this ‘anarchy’ thing going on. I was a bit of a rebel. I was still a big nerd. When I was at school, you’re either a Goth or a rocker or a townie,” says Martini, who’s wearing a pale pink dress with long sleeves and a plunging neckline.

A townie, she explains, “was, like, track suits and fake tans and hair extensions.

“I think some people made fun of me. But I think all the best people get made fun of when they’re at school. I think you do not want to peak when you’re at high school. I feel you need to have that struggle, that difficult, not-really-fitting-in, awkward thing in order to come out and smash it when you’re older. If you peak at high school, you expect life to be really easy.”

She didn’t expect life to be easy so she waited tables, clerked at a makeup counter, and taught youth theater while she dreamed of becoming an actress. But she had to try out twice before she was finally accepted at RADA.

“The first audition I was very under-confident and quite nervous and quite self-aware and I’d only just decided to go for it, decided that this was what I was going to do. So I was a bit too tense. I was also, at that time, working at a hotel, not doing any theater at the same time,” she recalls.

“I wasn’t involved in that life. The second audition, I was really involved in the theater scene, and I was doing lots of projects I was excited about at the same time I was doing the audition. And I had a bit more confidence in being excited and passionate about something. I also think drama school is so intense. Sometimes you need to be a little bit older, a little bit grounded in order to go into it and get as much as possible out of it.”

She admits that feeling inadequate is part of what she treasures about acting. “I like to be given things that I don’t actually have a clue how I’m going to do this. I really like that,” she says.

“I think to be put in a box would be boring, and nobody becomes an actor because they’re a safe person. You have to be a little bit crazy to do it in the first place.”