BBC One’s cold cases crime drama Waking The Dead returns this month for a ninth and final series. Sue Johnston has played psychologist Grace Foley since the show started in 2000.

Grace is a forensic psychologist and is fascinated by criminology. She has worked hard to change police attitudes towards her line of work and generally enjoys Boyd’s fullest confidence in her performance and analysis. Although that’s not to say that they don’t ever disagree. Unlike the rest of the team, Grace gets away with openly challenging Boyd. She has turned a blind eye many times when Boyd is violent with a suspect but hates being compromised in this way. Grace provides careful analysis with vivid empathy; she enters the mind of the criminal and can visualise everything the victim has been through.

> Order the Series 9 boxset on Amazon.

> Order the Complete Series 1-9 boxset on Amazon.

What memories do you have of working on Waking The Dead?

“When we filmed the pilot for Waking The Dead, we filmed outside The National theatre on the South Bank and the scene involved a lot of running. I was wearing heeled boots and ran and skidded and pulled my hamstring! The pain was awful I thought I had broken my leg. I was off for a few days but when I went back I had to be carried by paramedics up and down the set because I wasn’t allowed to walk on it, so it was very eventful.

“Oh and the first ever scene we filmed was in a land fill, the smell was awful. The cast and crew had protective clothing but then we’d go for a take and have to take all the protective clothing off. And so we were breathing this terrible smell.”

What have your favourite scenes from across the nine series been?

“Oh gosh, there have been so many. I really loved working with Holly (Aird) and Claire (Goose) from the original cast, it was fantastic.

“We’ve always had wonderful guest artists as well, Dame Eileen Atkins guest starred. The fact that all these incredible actors and actresses wanted to work on the show made me very proud. I very much enjoyed working with Paul Freeman, one of Grace’s old lovers, Grace has had so many old lovers! He tried to kill me in the end, luckily Boyd saved me.

“Another love story of Grace’s revolved around her first job when she’d just left university and graduated as a psychologist. Tom Ellis played Grace’s boyfriend and the young lady playing me was fantastic. I really enjoyed watching that episode.

“Some of my absolute favourite scenes were with Trevor; they’d just be simple conversations where we’d talk about life. As Boyd got angrier and angrier we stopped doing that. Trevor is such a great actor and I’ll always cherish the scenes we did together – when we would wing it – so to speak.

“We’d often shout at each other and over lap and I loved that the sound technician made it possible for us to do that. It is so weird to go to another job and not be able to do that. It does set you free in a way, you can just go for a scene.

“I also remember the Ruth Gemmell episodes, which I think are my absolute favourite episodes of all. Resulting in the episode where her character, Linda Cummings, was going to pump me full of drugs – in Series 8 – and again Boyd saved me. There I was dying of cancer but still not a dull moment.”

You were reunited in this series with John McArdle, who you co-starred with in Brookside. What was that like?

“Yes and again another old lover of Grace’s. To be reunited was wonderful. And I had to do a stunt which was great; I do all my own stunts. John appears in an episode called ‘Solidarity’. The stunt comes about because Boyd has set me up to try and get the truth from him. It puts Grace in a very dangerous position and she has this accident and she thinks she is ok and suddenly she’s down.

“In the 80s, when we started acting John and I were an item on television in Brookside. It was extraordinary that Grace’s back story should flash back to the 80s when we were together on screen.”

Eva Birthistle joins this series as Sarah Cavendish. What does she bring to the team?

“She’s such a good actress and the camera absolutely loves her. She slotted right in, she is such a warm person and so it felt as if she’d always been there. It is a great character Eva has produced with a very interesting back story.”

What have you enjoyed about playing Grace?

“The stillness of Grace, she listens but she is quite formidable. We watched a compilation DVD that Colin Wratten, the producer, had made to celebrate the end of the series where Grace was shouting at Boyd, it was quite brutal.”

Did you do any reading around the subject area?

“Well, I did talk right at the beginning to a psychologist. Right in the early days, and I based my research on those conversations – she came to my flat and we sat having a glass of wine, she was very sexy and open and warm, and I thought ‘oh you don’t have to be a certain way, you can be a human being,’ and I think that’s what we created, in the characters.

“Recognisable people, ordinary people, but with sort of extraordinary gifts, I suppose. I mean I used to feel so proud sitting in the office and looking at all the books and thinking ‘I’ve read all those’. I understand all those and I used to read a lot of those psychological books at first.

“And of course, I would go and look them up if we were doing particularly involved subject matters – and some of the words I had to say were so scary – and I remember David Thacker, one of our special advisors, used to direct us and say: ‘let it trip it off the tongue Sue, trip it off the tongue’. And sometimes they’d suddenly re-write the scripts, and there’d be this huge line of expletives, as far as I was concerned.

“David was absolutely right because though they use these words – like doctors in a medical series, when they’re rushing medical terms out, they would trip off the tongue, because they’re just words, they know what they’re talking about. I think that was the hardest thing.”

The dynamic between you all is one of the elements of the show viewers really love. How do you work together to create that?

“Well, I know it could drive people mad, when we take scenes apart and it sort of starts unravelling a bit – that’s been the way it’s been, for some reason with this show, from day one.

“I think it’s because it’s such a complex show to write, because there has to be police input, psychological input, and the forensics, and to find all those rooted through, and character – and often we’ve found with writers that they do great ideas and stories, but there’ll be less character, conversation and relationships.

“So I think that’s what we worked hard to develop, because actually all you can give the audience is what they’re seeing – because the characters don’t go home, you never see a life that people could relate to, they had to relate to us relating to the people we work with, and therefore it was very important to make those relationships work, and live and breathe as people that they would care about.

“That’s why people watch people TV, they want to share with you that bit of your life. If it was dull and we were just giving out facts it wouldn’t have worked as well, so a lot of that work has been trying to find different ways of making facts interesting and exciting, and I think it developed really well over the years.

“I think if the team care about the victims then the audience do, because we have very clever actors who bring the audience in. It can be difficult sometimes when the people that you need to care about are dead in the present day and so you need the squad to bring the audience in and make the audience care, and that’s something that happens very successfully on the show.”

Did you have much in-put into Grace’s wardrobe?

“When it started I wanted her to be very much how she probably would have dressed at university – slightly hippy, slightly off the wall, not clean cut suits… I like the layering – I think Grace actually brought layering in – and a bit floaty and slightly bohemian, like she would have been at uni, I can see her like that.

“It just developed on from there and the costume designer really picked up on it and we really hit ‘Grace’, you know, and we did get some really nice jackets, but she’d always wear long things underneath. This season I’ve got into skirts and boots, and I felt very odd, I don’t think I liked it very much, cause I’d sit down and I’d suddenly see my leg and I thought ‘You shouldn’t be seeing Grace’s knees’ It’s not right, somehow.”

What was filming the final episode, ‘Waterloo’, like?

“I will always remember it because even though we filmed it second, I had a sense of it being the end. The final scene under Waterloo bridge was fantastic. It is such a great episode and I love the shots of Boyd walking through London, walking to meet us. A great performance from Trevor, from everyone in fact.

“I shall miss working with them all, I shall miss Tara. I think Tara is fantastic and I loved doing scenes in the lab with her, I’d sit and look at how beautiful she was – she’d have died if she’d known, and such a beautiful person too.

“The crew were fantastic as well and they have been more of less the same crew since we started. I am really looking forward to it going out – to see how it is received.”