Later this month, Naomie Harris appears in her first starring role in a film. She is 43. What has taken her so long? Not laziness. Harris has always been a grafter, acting on TV from the age of nine, saving every penny to pay for university (social and political science at Cambridge, one of only two black students in her year). The work ethic, she says, comes from her mother, who discovered she was pregnant when doing her A-levels and raised her daughter solo, funded by a job at the post office. She later went to university, worked as a scriptwriter on EastEnders and is now a reiki healer.

So, Harris is no slouch. But for years she told her agents: supporting roles only. No leads. “I get consumed by the characters that I play, and acting is quite a stressful, adrenaline-inducing thing. So I didn’t really know how well I would cope with being a lead. It was partly a confidence issue, as well. I just thought I’d be biting off more than I could chew.”

We meet at a photography studio, where Harris is dressed in a floor-sweeping powder-blue gown (“dress” really doesn’t do it justice). When I walk in, she is comparing two croissants on the buffet table, one of them vegan, with a stylist: “Hi, we’re doing a taste test,” she says. Friendly and unpolished (she says “baddy” instead of villain), she has the slight stiffness of the very shy.

Harris with Tyrese Gibson in Black and Blue: ‘I hate guns, even when they’re empty or have blanks.’ Photograph: Alan Markfield/Sony

Harris doesn’t make many films. Not long after she left university, Danny Boyle took a chance on her in 28 Days Later. Two Pirates of the Caribbean movies followed. She was electric as Winnie Mandela opposite Idris Elba in Mandela: Long Walk to Freedom. Her arrival as the brainy Eve Moneypenny dragged the sexual politics of the James Bond franchise into the 21st century. Finally, there was a female character who wouldn’t hop into bed with 007 after a double vodka. (Harris insists on being referred to as a Bond woman rather than Bond girl.) Then came Moonlight, the film that earned her a first Oscar nomination, and for which she broke her golden career rule: to only make films with positive depictions of black women.

With her new film Black and Blue, the opportunity to play a role model is what grabbed her: “A black female cop as the lead – we don’t see that very often.” The film is a popcorn thriller with important things to say about police brutality against African Americans and the role of bodycams in policing the police. Harris plays a newbie officer who captures footage of fellow officers executing drug dealers with her bodycam. The movie unfolds over one long night on the streets of New Orleans.

Harris is an unlikely action hero: she hates guns. After three Bonds, she is still scared of picking one up, “even when it’s empty or has blanks”. And Black and Blue is a violent film. Her mum walked out halfway through: “She just couldn’t take it, bless her.” Harris kicks serious butt in the film, throwing burly men around; in one scene, she grabs a plank of wood to batter a bad guy senseless while unleashing a primal howl of fury. “I don’t actually like anger in everyday life,” she says. “I’m very, very sensitive. But I’ve done enough kind of self-development work to realise that actually anger is a really important emotion that needs expression. Because I bottle mine up, I find it really cathartic to just let rip. So on set I’m like: ‘Yeah, give me that plank of wood. I’m going to bash him up.’ I let it all out.”

Black and Blue marks Harris’s return to acting after nearly packing it in – at the height of her success. It was mid-2017, and for months she had been living out of a suitcase on the campaign trail with Moonlight. Immediately after the Oscars, she flew to Atlanta to shoot action movie Rampage with Dwayne Johnson. Afterwards, back home in London, she told her agent not to send any scripts her way.

Harris in Moonlight, 2016: ‘Once I connected to her pain, I could have empathy for her.’ Photograph: Alamy Stock Photo

“I was completely burned out. I needed a break,” she says. “I was like: ‘I don’t want to be an actress any more.’ I was thinking of opening a nail salon with my friend.” Actually, the plan was a little more ambitious: creating an eco-friendly non-toxic nail polish with a designer pal. In the end, the wobble resolved itself, thanks in part to a month-long retreat to India where she spent her days doing yoga and meditating. After an eight-month sabbatical, she opened her inbox to find the script of Black and Blue.

When her agents sent Harris the script of Moonlight, it was caveated with an apology. “They were like: ‘I know this is a crack addict, so we’re really hesitant to present this to you, but …” Harris is teetotal and has never taken drugs. At first, she worried about being able to pull off playing an addict. Then she started watching videos on YouTube, interviews with female addicts filmed in crack dens, all of whom had been sexually abused. “Every single one. Once I understood that, I was able to tap into her unresolved, unacknowledged pain. That’s what drives her addiction and the addiction causes her to be a monster to her own child. Once I connected to her pain I could have empathy for her.”

Harris’s own mother, Lisselle, raised her daughter on her own in a council flat in Finsbury Park, London, and she has had little contact with her Trinidadian father. She and her mother remain close; she lives on the same street as her and her stepfather.

Harris’s personal life is not up for discussion – she doesn’t have children and told a magazine that she is sick of people (friends as well as journalists) asking if she wants to start a family. Yet she appeared on the BBC genealogy show Who Do You Think You Are? earlier this year, in which she discovered she was descended from both slaves and a slave overseer. She showed a lovely photo of her with her maternal grandfather, who was a huge part of her upbringing and forever showing up with packets of flannels as presents.

Harris remains very practical. “I don’t want to be sent a designer bag. I’d rather be sent a vacuum cleaner. My mum gets me stainless steel pots for Christmas, or a salt grinder. I’m like: ‘Oh my God, amazing.’”

Since the programme, there has been surprise that she knew so little about her past before. “But that’s a first-generation and second-generation immigrant thing, to not explore the past because everything’s focused on success, success, move forward, let’s make a better life for the next generation.”

She adds: “The past is also quite ugly and it’s so painful because it’s so recent, so you don’t talk about it.” Her mother, who arrived aged five from Jamaica, experienced “horrendous” racism, she says. It is something she worries is on the rise. “I think it’s very easy to excite in people racist tendencies.”

Harris with Daniel Craig in Skyfall, 2012: ‘We want a Bond that inhabits the qualities we associate with Bond.’ Photograph: REX/Shutterstock

Harris speaks carefully; she worries that opinions will get reduced to soundbites. In 2017, she told the Times that she had never experienced racism or sexism in the film industry. Today, she admits that is not quite true. In her mid-2os, she was groped by a very famous actor. “I was in an audition and he put his hand up my skirt. What was so shocking about it was the casting director was there and the director, and of course no one said anything at all because he was – he is – such a huge star.” In a way, she believes her Cambridge education protected her to some extent from misogyny in the film industry. “I think there is the immediate assumption that you have a brain. Which is not necessarily true if you go to Oxbridge, as I’ve discovered.”

Time’s Up has seen a “massive shift”, she thinks: “Men know that they absolutely cannot get away with things now that they wouldn’t even have thought about before.”

Including, it seems, 007. Next April will see the return of Harris as Eve Moneypenny in No Time to Die, alongside a newly woke James Bond, dialogue courtesy of Fleabag. Phoebe Waller-Bridge was brought on board at the 11th hour to jazz up the script – and, says Harris, even when she wasn’t on the set, she was present. “If there was a problem with the script, then [director] Cary Fukunaga would always be like: ‘OK, well, I’ll just make a call to Phoebe.’”

The film is reportedly Daniel’s Craig’s final outing as Bond. One of the frontrunners to replace him, Cillian Murphy, recently ruled himself out by saying that 007 should go to a woman. When I put this to Harris, she gives what feels like a rehearsed line: “I think we want a Bond that inhabits the qualities that we associate with Bond. Whatever sex that is, whatever race.”

Might Moneypenny take over? She splutters. Yet Black and Blue proves she can chuck a baddie over her shoulder. “It’s weird. When I was watching it, I was like: ‘Oh my gosh, I am an action hero in this movie. This is not how I envisioned my career at all.” As for her conversations with agents, they’ve taken a new direction. “Now I’m like …” – she puts on a diva trill – “‘Leads only please.’”

Black and Blue is out on 25 October