Speaking about her cameo, Tracy-Ann likened the prison showdown to Orange is the New Black — calling upcoming scenes “brilliant” and “fun”.

“When I read the script, I just kept thinking this is like Orange is the New Black meets Prisoner Cell Block H, meets Bette Davis and Joan Crawford. It was just great,” she said.

“I’ve had so many years of people asking me what happened in Chrissie’s court case, and if she would ever come back because people loved that character. I sometimes would wonder what Chrissie was up to so it’s really lovely to be able to come back and revisit that woman. I have to thank Tony Jordan and Sarah Phelps for creating that character and writing for her so well.”

Tracy-Ann joked that Chrissie has been in prison “longer than real murderers”, before teasing how incarceration has changed the baddie.

“I’ve always said if she had a better lawyer, she would have got off for mitigating circumstances. I think it’s made her tougher,” she said. “I think it’s made her very singular in her own survival and I think it’s given her a long time to think about that relationship with Den, and what he drove her to.

“I don’t think she’s softened, if anything I think she’s gotten harder because she’s had to survive. She’s obviously had a really tough time in prison and let’s not forget that she put Sam Mitchell behind bars, and the Mitchells have got long arms that reach into all sorts of areas.”

The actor went on: “I kept having to try and work out why Chrissie had been in prison over the last 19 years because as I say, it’s longer than most murderers, so obviously stuff has gone on in prison that has kept her there!

Two decades behind bars have allowed Chrissie the proper time to contextualise her broken marriage to the abusive Den Watts.

“I think she’s had time to realise what a horrible, toxic man Den Watts was,” the actor said. “She also understands that relationship a lot better, and how he was the sort of man that could get under your skin as a woman, and how he could push you to the edge. He was an arch manipulator, a liar and a coercive controller, and twenty years on, the reality and understanding of that relationship has really sunk in.”

Teasing a showdown with Sharon, Tracy-Ann hinted: “It’s the meeting of two strong Watts women, but 19 years have elapsed. Is Chrissie pleased to see an old friendly face? Or has she used the last 20 years to fester on what Sharon did to her which was not letting her escape with Jake, the love of her life.”

While Sharon and Chrissie are bound to butt heads, Tracy-Ann shared how close she is to co-star Letitia Dean off-screen.

“Oh my god, Tish is a joy. We were very close 20 years ago, and life takes you down different paths so we hadn’t really run into each other,” she explained. “We both looked at each other after a couple of scenes and went ‘wow, this is really good’. We work extremely well together. We both work really hard, but we laugh a lot, and she is an absolute joy; I just love her.”

Describing their scenes together as “so fun”, the actor continued: “I’ve spent the last year in Shakespeare land playing a very intense character in Shylock against a very harsh setting of 1936 fascism, so to come straight out of that and to go in playing Chrissie with Sharon in prison was the biggest joy.

Tracy-Ann previewed what fans can expect from next week’s blockbuster confrontation between Sharon and Chrissie, promising it will be “a real rollercoaster of a ride”.

“They were once extremely close but Chrissie murdered her father and lied to her about it, but equally they did trust each other, and they both understood each other very well. I think all the emotions will be present – love, jealousy, hatred, passion, joy and revenge,” she said.

“Will there be a resolution? That is the big question over the week and will they both come out of it alive and will they both come out of it with some closure? Who knows…”