Until I Kill You star chose not to meet real Delia Balmer to research role

On whether she had any conversations with Delia before filming, Martin told ITV in a press pack for the series: "No, I’ve played quite a few real people and I have never met them before. I don’t choose to do that, that’s how I work.

"Our writer, Nick [Stevens], filmed a lot of footage of his meetings with Delia, which I had access to. I did meet her very briefly during filming, but only because she wanted to visit the set, and of course I was respectful of that."

Martin continued: "I didn’t do lots of research into abusive relationships either, instead I just focused on the character, on who she was, how she responded to things, and what I could gauge about how she interacted with people.

"Then you go from there and you try to be as accurate as you can in terms of how that person would behave and respond."

The four-part series is based on Balmer's book Living with a Serial Killer, and follows Delia as she goes on an emotional journey through the police and criminal justice system as they attempt to prosecute Sweeney (Shaun Evans) for his crimes.

Evans, who is of course known for his leading role in Endeavour, takes on the role of the murderer, and also revealed that he didn't research the role in the way that some may expect.

When asked about what research material was available to him in preparation for the role, Evans said: "I don’t really work in that way, to be honest with you. That’s not to dismiss it, but that’s just not what works for me personally.

"I think the imagination is limitless, and I’m slightly more concerned with making the story that we’re telling as believable as possible than the impression of somebody who may have existed.

"I think you have to invest in the day-to-day of what we’re doing, so a lot of it was just imagination to be honest."

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The official synopsis for the four-parter reads: "In 1991, Delia leads an itinerant and solitary life in London working as an agency nurse. When she meets fellow free spirit John Sweeney in a local pub, it seems like the connection she has been searching for.

"As the relationship develops, Sweeney's artistic, anti-establishment persona gives way to a darker side, culminating in a series of violent attacks on Delia, during which he tells her he killed his former girlfriend and disposed of her body in an Amsterdam canal.

"Sweeney is arrested but, due to a catastrophic failure by the court to realise how dangerous he is, granted bail. He immediately pursues Delia and subjects her to a horrific, near-fatal attack. She survives, but Sweeney evades capture and disappears."

It continues: "Shattered by the trauma and injuries inflicted by Sweeney, Delia bravely seeks to rebuild her life. But Sweeney returns seven years later and is arrested for the murder of another girlfriend in North London.

"Delia's fragile recovery is shattered all over again as she has to face Sweeney in open court, her testimony vital to the prosecution case against him.

"This is the story of one woman's astonishing will to survive through physical and emotional torment, despite the failings of the institutions which were meant to protect her."

Until I Kill You will air on ITV1 and ITVX from Sunday 3rd November to Wednesday 6th November at 9pm on ITV1.

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