The long-awaited fourth series of ITV's Unforgotten finally arrived earlier this year – however, its dramatic finale left viewers distraught when news broke that Cassie (Nicola Walker) had died from brain injuries sustained in a tragic car accident.

Walker has recently spoken about the death of her Unforgotten character, revealing that she "loves the irony" of Cassie's demise, which both she and creator Chris Lang decided was the best way to end her story.

"Chris Lang and I had been discussing the storyline for Cassie since the first series. By the time we got to her nervous breakdown in series three, we were already talking about where that story might naturally go, so her sudden death was very much a joint decision," she told Radio Times magazine.

"I’m not on social media, but when the final episode went out, I almost wanted to join Twitter to tell everyone that I didn’t walk away from the show, nor did they ask me to leave. It was simply that Chris and I thought it was a fantastic, impactful story.

"I love the irony of this brilliant woman dying an accidental death that wouldn’t be investigated in a show about complicated investigations."

Walker added she wasn't surprised by the public outpouring of grief as it had been a difficult scene to shoot. "We hoped people wouldn't feel we were being cruel by serving up this incredibly sad story."

Unforgotten will return for a fifth season with Sanjeev Bhaskar reprising his role as Sunny, who'll be joined by a new female partner, Lang recently confirmed to

Check out the full interview in this week's edition of Radio Times magazine. For the biggest interviews and the best TV listings subscribe to Radio Times now and never miss a copy. Wondering what else is on? Check out our TV Guide. Visit our Drama hub for all the latest news.