Sheridan Smith on her return to the limelight: "I'm trying to be a bit more grown up nowadays"

Smith is lauded for her ability to get under the skin of her characters and, when asked whether she identifies with Sam, she laughs: “I don't know about gambling, myself. I've got plenty of other vices, but that isn't one of them…

“I loved the working-classness of Cleaning Up. That's where I'm from, they're the type of people that I would naturally attract to and want to be around, so I loved it.”

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Alongside Channel 4’s Adult Material and BBC1’s Care, Cleaning Up is one of a string of new parts Smith has taken on after a hiatus from acting.

Smith suffered a very public breakdown in 2016 following her father's death, but reveals that recording her second album, A Northern Soul, this summer felt “therapeutic”.

“I enjoyed being able to turn up to the studio looking like s*** and it didn't matter,” she says. “And to not be filmed and lose myself a bit and get stuff out – a bit like therapy.”

Smith says she no longer watches herself on television: “Not anymore. And I don't read anything anymore. I've learned.”

Although working on music again was a positive experience, Smith was keen to get back to acting. “My acting is what I love more and I've realised lately that I really want to get back to it because I just love it,” she says, “I love losing myself in these characters…

“It's just quite empowering to be able to take control a bit more and do things I really want to do… I'm trying to be a bit more grown up nowadays.”

Part of being grown up has included moving to the countryside, where Smith has set up a farm complete with four donkeys, two goats and two pigs – a place she can escape to in between her busy filming schedule.

Cleaning Up’s executive producer Chris Fry says that filming the drama was “tough” for Smith. “It was a different experience for her because she usually shoots things that are much shorter and factually inspired,” he explains.

“So to do a six-part series – she was in almost every single scene – as well as promoting her first album at the time, it was tough for her. But she was the leader of the troupe, she really was. And she came in every day and she was brilliant, she inspired everyone to do their best work.”

Smith admits that she does find it easier filming the fact-based dramas for which she is acclaimed, such as Mrs Biggs, Cilla and The Moorside. “It’s something that I have to stop,” she says, “because that's my preference of what I like to watch but I can't just do that… [With fictional dramas] I found it hard not having the research that you've got [with real people]. There was years worth of stuff with Cilla and I spent months throwing myself into that, you've got that to back you up, whereas with this it's just like, ‘Go on then.’

“Maybe it's an insecurity thing, that I didn't have that [research] to fall back on. I felt on the set [of Cleaning Up] sometimes a little bit like, ‘Ah, I don't know what I'd do here.’”

Cleaning Up is penned by a brand new writer, Mark Marlow, who conceived the idea for the series when he was watching the 1987 movie Wall Street and noticed there were cleaners in the background of a scene where Charlie Sheen’s character breaks into an office to find inside information. “I just instantly thought, ‘Well if they work in that office surrounded by inside information, why couldn't they just do that?’” he says.

Marlow admits that having Smith, an actress with national treasure status, starring in his first ever drama feels “slightly surreal” and “too good to be true”, but the show’s producer Jane Featherstone explains why Smith was the perfect fit to play Sam.

“She's real, she inhabits Sam for real. She just takes on the cloak of these characters and finds such truth in it always, it's an amazing gift to have. And to be so accessible to an audience – [Sam is] a really flawed, complicated character and whatever she does you're going to love her and be interested in what she's doing. You're just on her side, I think.”

Marlow adds: “With Sheridan we've got someone so empathetic as an actress that you just want to root for her, that's why she was so great for the role.”

Asked whether she would do as her character Sam does and participate in insider trading if it meant providing for her family, Smith grins: "Yes. Defo. I would, sorry. Morally wrong, always!"

Cleaning Up premieres on ITV in January 2019