Life could have been very different if Siân Brooke, aged 10, hadn’t gone to see a musical adaptation of Banana Boys at Lichfield Art Centre. It’s a vivid memory that, more than 30 years later, she still credits with opening her eyes to the world of performing – and one that ultimately spurred her on to pursue a life on stage. “I remember being part of this tiny audience but being completely mesmerised and lifted up inside. I’ve been chasing that feeling ever since and I wanted to be involved in telling those stories. I did everything you could think of: operatics, drama clubs, Shakespeare in the Park, and pantomime.”

Quite the humble beginning for an actress who lists The Moorside, Sherlock, Doctor Foster and, the reason why we’re chatting, Blue Lights on her CV. Reprising her role as response officer Grace, Brooke returns to our screens tonight (29 September 2025) in the third season of the BBC-produced, Belfast-set crime drama. But it seems the novelty of working on this BAFTA-winning show hasn’t worn off yet. 

“I enjoy playing Grace because she believes in the possibility of change,” says Brooke. “She’s not afraid of stepping out of line if it means some good will come out of it. That involves bravery, defiance and she’s a bit messy and annoying in her pursuit of this sometimes. I think we need a bit more of that in the world today; it’s so easy for us to feel downtrodden, that change isn’t possible, and become overwhelmed and apathetic.”

Siân Brooke as Constable Grace Ellis in the BBC’s Blue Lights. Image: BBC

We meet Grace in season one as the mother of a teenager who, in her 40s, has decided to leave her job in social work to join the Police Service of Northern Ireland. Brooke stars alongside Nathan Braniff as Tommy Foster and Katherine Delvin as Annie, completing the trio of rookie cops who all joined the force for very different reasons. Now, in season three, the squad are well versed in the highs and lows of policing and are leading the charge against a global gang ruling Belfast. 

Brooke’s character development has been nothing short of exceptional, spotlighting a woman transitioning from being a lay member of the public to a life in uniform and service. But it’s something that came relatively naturally given her father was a police officer. “I remember reading the script for the first episode [of Blue Lights] and what jumped off the page was that they captured what I knew in terms of the behind the scenes policing. 

“I didn’t have that barrier between being a member of the general public and life in the police and uniform. I saw [my dad’s] uniform hanging up in the wardrobe, I’d been in a police station and in an interview room, so growing up I could see that there was a person behind the uniform. Only now do I realise that most people don’t have that.”

Born and raised in Lichfield, Brooke says no one could have predicted she would have enjoyed being in the spotlight: “I was quite shy as a child; my mum says I was like her shadow and clung to her leg; I was very reluctant to leave. I wasn’t an extrovert [and] I think it’s still very much part of me. I’m not the most outgoing in my personal life. Acting is about becoming someone else and the purpose is the story.”

During our interview, mother-of-two Brooke mentions she has just returned from her native Lichfield to celebrate her youth theatre’s 40^th anniversary – a place she holds dear for many reasons. “I was really lucky that there was a thriving amateur dramatic scene; I look back and there’s no way I’d be doing what I’m doing now without these people who gave up their time for free. We’d gather on a Sunday and it was the highlight of my week. This wonderful woman called Pat Gibson inspired all of us; we’d do musicals, we’d do Greek tragedies and improvisations, all for free.”

Brooke is acutely aware of the platform amateur dramatics gave her – something many aspiring and budding performers don’t have without grassroots, community projects. Talking of the importance of these organisations for providing launchpads into drama schools, Brooke explains: “I champion it. I’d never thought this was possible had it not been for people who gave me a platform to grow a passion. 

“When I applied for drama school I didn't think that was possible; the only reason I did apply was because my mentor said ‘why can’t you?’. The way the world is now, and the expense of drama schools and training, will limit the industry if we don’t have grassroots level opportunities for kids from all backgrounds to be able to enter into the arts.

“If I told a 16-year-old me that I was going to work with Mike Leigh and all these people, I would not have believed it. Leigh was a real highlight because he gave me the opportunity and the confidence that this was a proper job and I had the ability to do it – and Sherlock was a game changer.” 

Brooke trained at the Royal Academy of Dramatic Art (RADA) and graduated in 2002. Her early career was dominated by theatre and stage, including a roster of roles with the Royal Shakespeare Company, playing opposite Benedict Cumberbatch as Ophelia in the Barbican's 2015 production of Hamlet. 

TV came later – Brooke is famous for her role as Eurus Holmes in BBC’s Sherlock – but she is grateful for the time she spent treading the boards of London’s stages before going in front of the camera. “I’m very glad I started in theatre and got my stripes. [This career] is a marathon not a sprint, and I learned what kind of actor I am around different directors and actors. I will always be grateful to theatre for giving me an understanding of writing.”

Now in its third season, Brooke first got the call for Blue Lights in 2023 and is already preparing for the next instalment. “When we were filming series two, the BBC commissioned three and four. I’ve never had that in my career before; it was amazing because it can be so uncertain and unpredictable,” she explains. 

“It’s so great as an actor to come back and revisit a part that you’ve created with people who started at the same time. We were all holding each other’s hands and stepping into the unknown in season one and every time we come back it has been well received. In terms of it getting better and better, one would hope it would inevitably do that because everybody is bedded in terms of what their craft is.”

Faith, a BAFTA and a seven million-strong audience keeps Blue Lights alive, but it’s the people that makes it a joy for Brooke. “When we first embarked on creating Blue Lights, our director, Gilles Bannier, was phenomenal in the way he crafted that world and gave us as actors freedom and confidence to play with it. Plus, the stunts and the high octane stuff are not your everyday.”

None of which, of course, means Brooke is limiting herself just to the crime genre. She is currently filming Trying for Apple, which is in its fifth series, then will come the superhero-fantasy Supacell for Netflix, and season two of The Undeclared War. She knows she’s lucky to be busy – but if there’s one thing that’s clear about Brooke, it’s that she doesn’t take anything for granted. 

Interviews like this, she says, always make her pause and reflect, and if she could tell that aspiring young actress from Lichfield anything, it would be: “Have more faith in yourself and don’t worry so much about others because you can’t control it – and don’t sweat the small stuff.”

Blue Lights season three airs on BBC One from 29 September 2025. 

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