Blue Lights: The police drama hitting home in Northern Ireland

"Whether it's your friends or your family, everybody has their own relationships with, and viewpoints on, the police," says Dearbháile McKinney, star of BBC drama Blue Lights.

The Londonderry actress and her co-star Katherine Devlin, who also grew up in Northern Ireland, say relationships between police and communities there were at the forefront of their minds as they prepared for filming.

The Bafta-winning series follows police officers working at the fictional Blackthorn Station in Belfast.

But, for many watching, the drama feels all too real.

The difficulty police in Northern Ireland still face was thrown into focus this weekend by the long-running dispute over the controversial Garvaghy Road parade route when officers had to prevent a march by Protestant Orangemen through a largely Catholic area.

Many scenes in Blue Lights highlight the distrust of, and hostility towards, the police in some communities.

Warning: This article includes spoilers for the first three seasons of Blue Lights.

Devlin plays Annie Conlon, whose storyline deals with her having to move away from home as a result of death threats because she's from a Catholic family.

"We do have similarities - she comes from a Catholic background and so do I," Devlin tells BBC Newsbeat. "I know girls like Annie.

"But I've realised we're different in a lot of ways. Mainly, to be honest with you, I wouldn't go into the police."

Devlin says that forming Annie's character was about trying to understand why she decided to become an officer and "for that to be the crux of her story".

"I think a huge thing with this season is the idea of home and what home means to her," she says.

"Just battling that inner dialogue that she has with 'is it all worth it?'

"Especially her being a Catholic and the intricacies of that and the politics of that.

"It's heavy stuff and she has to really think about it."

The Police Service of Northern Ireland (PSNI) had its lowest number of Catholic applicants in more than a decade earlier this year, with some pointing to "fear and apprehension" in those communities putting them off joining the police.

One of the force's when it was founded in 2001 was to build broader community support and increase Catholic officers.

At the time, only 8% of the force was from that background. It's now at 32%.

In a statement sent to Newsbeat, Chief Constable Jon Boutcher said the PSNI was "totally committed to being more representative of the communities we serve".

"I am deeply concerned at persistent and often unjustified criticism and the outdated and unsupported views of dissident paramilitaries remaining as barriers to people seeing themselves having a career in the police," he said.

Boutcher said he "absolutely" accepted the PSNI needed to do more to diversify its recruitment but could only do so if "people in all communities in Northern Ireland see policing as a career for them."

He said the force planned to launch a new student officer recruitment campaign "in the coming weeks".

Blue Lights is filmed locally and on set in east Belfast you can spot the attention to detail, right down to the information leaflets at a police station reception area and case folders on officers' desks.

"It's really lovely just to see the amount of people who see themselves in the characters," Devlin says.

"And [mention] how cofmplex the characters are. How real and human they are".

It's something McKinney considered in how she plays Aisling Byrne.

Aisling struggled with Post Traumatic Stress Disorder (PTSD) in the last series, something Dearbháile says she spoke to real-life officers about.

"They've had to witness some horrific things and been left with PTSD and trauma that they just have to learn to live with," she says.

"It's the reality here. It would be ignorant to not think about that."

Aisling's condition puts a strain on her relationship with Tommy Foster, played by Nathan Braniff, who is then faced with the decision whether to report her to their bosses so she can get help.

And while Braniff says Blue Lights often deals with heavy themes, he believes it does a good job at showing what Northern Ireland is really like.

"It shows that Northern Ireland's moving forward and changing all the time."

One thing that's changed for the fourth series is the public interest when the actors are filming scenes in Belfast city centre.

"After having lived here my whole life, it's funny walking down the streets of Belfast and bumping into people that I know wearing my full police costume," Braniff says.

"The support for the show here is unmatched."

Frank Blake, who plays Shane Bradley, is one of the few actors who isn't from Northern Ireland but he says he felt the same welcome, thanks mainly to a scene where his character opens up about his love of a certain Westlife song.

"We were shooting in town, and someone drove past blaring World of Our Own out of the speakers," he tells Newsbeat.

"I've long been a Westlife fan and it was great craic. It's so funny seeing how it really took off."

Series four of Blue Lights starts on BBC One at 21:00 BST on BBC One and is available to watch on iPlayer.

Listen to Newsbeat live at 12:45 and 17:45 weekdays - or listen back here.