After a run of portraying real-life ladies in Mrs Biggs, Cilla and The C Word, the unstoppable Sheridan Smith reveals fiction is just as emotionally demanding as real-life roles…

You star as PC Jo Gillespie in ITV’s new three-part thriller Black Work. How did you find it playing a fictional character after Cilla and The C Word?
“I thought playing Jo in Black Work would be a lovely end to a year of fictional roles and not as hard as Cilla or The C Word. But it’s harder because it’s a psychological thriller all seen through Jo’s eyes! Basically I’m having a breakdown as Jo’s husband Ryan has died and her grieving process is to find out how he was killed, while knowing that things are being hidden from her. There’s a lot of upset, anger and paranoia, so my head was a little mashed!”

When you play someone like Jo, how hard is it to get into and out of character?
“Because I never trained I don’t quite know how to turn it on and off. So I find I have to go to some quite dark places and stay in them. The funeral scenes in episode two are totes emosh. I was crying all the time.”

How does it compare to your other recent roles?
“On Cilla I was having a scream and singing away. And The C word was very close to my heart. But because Black Work is a psychological thriller, it messes with your head a bit. But that’s what it’s supposed to do. The audience are going on a journey with me and sometimes they’ll wonder ‘is she paranoid?’”

Jo discovers her murdered policeman husband Ryan (Kenny Doughty) has been working undercover for three years without telling her. How does she cope with this?
“When Ryan’s killed suddenly everything unravels. Jo comes to realise that for three days a week for three years Ryan wasn’t training police officers in London, but had a whole other life. She finds out terrible truths she never knew, while grieving for a man who had so many secrets from her. It’s really heartbreaking, but Jo’s a tough cookie. She realises something’s not quite right and the police are covering something up so she makes it her mission to find out.”

Who does she trust to help her answer her questions about Ryan’s double life?
“Both Jo and Ryan are police officers, so there’s the police family and her own family. After Ryan dies Jo starts doubting a lot of people in the police force, who are like family to her. Meanwhile her own family is breaking up, especially her relationship with stepson Hal. Jo really doesn’t trust anyone. It’s a real, fast paced whodunit!”

This is your first time playing a copper on British telly. How have you found it?
“It’s so different to anything else I’ve ever done. I’ve never worn a uniform before – I quite like it! You rarely see me in uniform throughout the three parts because Jo’s doing her own investigation and is mainly in her own clothes. It’s great because there are so many cop shows we didn’t want Black Work to be just another one. It’s not that, it’s a psychological thriller with a police side.”

Is there a lot of action?
“There is! They put a steadicam on a quad bike. I remember thinking ‘How fast do they think I can run?’ I went to boot camp for the role, but I was about three weeks too early and started eating pizza again!”

Matthew McNulty plays DS Jack Clark, Jo’s close friend Jack. What can you tell us about their relationship?
“There’s a complication… Jo and Ryan had marital problems so she was hanging out with Jack. They didn’t do anything, but it’s part of Jo’s guilt and grieving, and the reason why she wants to find out who killed her husband. So much happens along the way! The thing about doing a whodunit is you have to be careful not to give it away or no one will watch it! There’s a thrilling ending!”

Black Work premieres on ITV on Sunday, June 21 at 9pm. It also stars Geraldine James and Phil Davis, The Zoo’s Honor Kneafsey, as Jo and Ryan’s daughter, Melly, and Douglas Henshall as DCS Will Hepburn.

Watch our special feature, the A-Z of Sheridan Smith