Exclusive – Unforgotten director reveals Easter egg hidden in episode 3

The second episode confirmed the headless corpse in the freezer belonged to Martin Walsh, with our four Unforgotten suspects clearly dreading the ensuing investigation the revelation will incur.

Episode three promises to be just as tense, with Cassie ready to take down high flying officer Liz Baildon (Susan Lynch) if she must. But the episode will also feature a nod to another classic ITV series, which was a deliberate move on the director's part.

In an exclusive interview with RadioTimes.com, Andy Wilson revealed he used a picture of Lynch that references an episode of Cracker he directed almost three decades ago.

"In this episode, we see a photo of Susan Lynch's character Liz Baildon as a 21-year-old police probationer in a file Cassie looks at for the Hendon Police Academy," Wilson revealed.

"The photo I used is a publicity still of Susan as the villain Tina from a Cracker episode (To Say I Love You) she starred in and which I directed in 1993. I liked having both of Susan’s characters in the show somehow. I hadn’t worked with her in all the years between."

The Jimmy McGovern series starred Robbie Coltrane as hard-drinking criminal psychologist (or "cracker") Fitz and a young Christopher Eccleston as DCI David Bilborough.

The Easter egg is a nice way to honour Cracker, but could it also hide a deeper meaning? Considering Lynch was the villain in the classic crime series, could she also be the one responsible for Walsh's death in Unforgotten?

The new series of Unforgotten is quickly becoming the show's most successful to date, with the first episode garnering 7.4 million views, becoming its most-watched episode ever.

Unforgotten continues on Tuesday 9th March at 9pm on ITV. Check out what else is on with our TV Guide or visit our Drama hub for the latest news.