Siân Brooke: Blue Lights has made me think I'm a real cop

Siân Brooke has become so absorbed in playing a police officer that she recently conducted her own stakeout in London. Suspicious of some activity near her home, she drove past slowly a few times, hoping the people involved would notice they'd been spotted. Her husband had to remind her she wasn't actually a cop. She laughs about it now, but the four years she's spent on the set of Blue Lights, the BBC's Belfast-set police drama, have clearly left their mark.

For the show's fourth series, which returns with what producers are calling "their toughest shift yet," Brooke plays Constable Grace Ellis—a social worker who switches careers in her 40s to join the Police Service of Northern Ireland. The new season opens with anti-immigration protests that spiral into full-scale rioting outside a migrant centre. Brooke was Bafta-nominated this year for the role, and the intensity of filming those sequences left her with a genuine injury. She pulled a muscle during the action work and didn't realize it until she tried to draw her gun during a scene. Steroid injections followed. When asked if her dedication rivals Tom Cruise's stunt work, she grins and notes the key difference: "The only difference is he jumps off cliffs, whereas I pulled a muscle picking up a wheelie bin."

What made those riot scenes particularly striking was their prescience. Weeks after the cast filmed them in spring, anti-immigration riots actually erupted on the streets of Belfast. Brooke credits the show's writers, Declan Lawn and Adam Patterson—both former Panorama journalists—with their meticulous research and their ability to capture the pulse of current events. The scripts read almost like documentary, she says, urgent and authentic. The show's commitment to realism extends to every detail. Police advisers are constantly on set, including specialists in public order policing who explain protocols and how to manage disturbances. Before the first series, the entire cast underwent firearms training. Now they receive regular refreshers on how to hold weapons, where to position their trigger fingers, the mechanics of it all.

But realism comes with unglamorous costs. The PSNI uniform, complete with stab vest and tactical belt, is a bulking, awkward thing to wear. Brooke has asked real officers how they manage to run while wearing all that gear. The answer: everything flies off in different directions—pepper spray one way, notebook another. During filming, her flak jacket refused to stay in place. Every time she climbed into the squad car, it would ride up until she resembled a Teenage Mutant Ninja Turtle. The costume department's solution was to insert a piece of wood down the jacket to weigh it down. For two series, she walked around with a chopping board inside her uniform. Cast members would knock on it and make jokes about her wooden acting.

Brooke's father, who spent many years in the police force, was sent the scripts when she first got the role. He agreed the show captured the camaraderie and banter of the job authentically, and he's been a devoted viewer ever since. He plans to binge the new series. Police officers have told her they're moved by how the show illuminates the difficulties of their work. She's even inspired career choices: a friend's daughter has said she wants to join the police because of Blue Lights.

The fourth series explores how social media can mobilize communities and endanger individuals. In the show, someone reveals Grace's identity online, putting her safety at risk. Brooke worries about social media's addictive pull and its societal impact, especially as a mother to two teenagers. She recently appeared in The Undeclared War, a cyber-thriller about how social media infiltrates politics. "It's frightening stuff," she says.

Brooke's path to Blue Lights was built on a decade of stage work followed by a television breakthrough in 2017. After playing Ophelia opposite Benedict Cumberbatch in Hamlet at the Barbican, she reunited with him for BBC's Sherlock, where she played Eurus, the detective's secret sister and master of disguise. She had to audition three times before being told all three roles were the same character. Her children are now old enough to watch Sherlock from the beginning, and she anticipates they'll be startled when they reach series four and discover their mother's involvement.

She had a brief but violent turn in HBO's House of the Dragon as Queen Aemma Arryn, who dies graphically during childbirth in the first episode. She would have loved to ride a dragon, but the script had other plans. Her current work includes a role in Netflix's Supacell as Victoria Kesh, a shadowy bureaucrat whose villainy intensifies in the second series, and Apple's Trying as Karen, an outspoken character she relishes playing. Next year brings Mavis Eccleston, an ITV drama based on true events: an 80-year-old woman who survived a suicide pact with her terminally ill husband and was later accused and acquitted of his murder. Brooke plays their daughter Joy, a real person she's met several times. The story took place twenty minutes from where Brooke grew up in Lichfield, Staffordshire. Playing real people carries weight, she says. "You feel a huge sense of responsibility."

Brooke has become an ambassador for two charities. While researching a Blue Lights storyline, she connected with Macs, a Belfast-based organization helping young people experiencing homelessness and leaving the care system. She also supports the Glacier Trust, which addresses climate change adaptation and is currently responding to flash floods in Nepal. After fifteen months of continuous work, she took a break this summer to spend time with her children, though she suspects they grew tired of her by the end of six weeks off school. She's now advocating for a five-week summer holiday with an extra week added to the October half-term—a campaign she jokes could launch her toward education secretary.