"You're my mind telling me this is real. If my body's lying in a hospital bed somewhere then my brain's created this."
What is Sam like?
"When you first see him, in 2006, he isn't particularly likeable; he's quite pedantic and anal, and he doesn’t seem to have much of a sense of humour. So when he wakes up in the Seventies it's quite a shock to him.
"For Sam it's an absolute nightmare – it's like some crazy mad dream he's having and he just can't wake up. That's a really frightening thought for anyone; to be trapped in a completely alien world.
"So he's a bit all over the place, as you would be. It really makes you think 'What if?'"
Sam doesn't get off to a great start with his new boss, Gene. They develop a love/hate relationship although they do have a begrudging respect for each other’s methods... How does he get on with the rest of the team?
"They rub off on each other I think. They learn to work together even though they are completely different. Gene's the boss and they have all learnt from him but Sam's methods influence the rest of CID especially Chris.
"Sam can't stand Ray but he likes Chris and he tries his best to teach him stuff but even Chris thinks he's a little odd. He says 'I don't underestimate you boss, I just don't understand you' and it's as simple as that. I think they probably all feel like that.
"Sam has the knowledge of how things are going to turn out and he knows about things like multi-tasking and taping interviews and they do it and they take it on board.
"His knowledge of the future is his only weapon and the only thing he can work with. And it's quite hard for Gene to take on board because he just thinks Sam's a nutter!
"But Sam learns from Gene too - a little humanity and using his gut instinct. It's a perfect 'buddy-buddy' cop thing but with a really weird twist to it."
Did you enjoy working with Philip? You have quite a lot of punch ups with him...
"I loved those funny fights and there's always a stakeout or a chase or something, and I love those.
"In episode seven, Sam, Gene and Ray are doing a stakeout at the technical college, looking for the drug dealer, and when they need to give chase they can't get out the car because the doors get stuck.
"That slapstick side of things just smacks of 1970s TV and I love that about it."
You are known as a serious actor, with a great CV including State of Play, Sex Traffic and Crime and Punishment, so people probably don't remember you doing comedy on TV although one of your first shows was Men of the World. Do you enjoy the comedy in Life on Mars?
"I enjoyed Men of the World. I do like doing comedy, I was in Spaced and I did a sketch thing with Steve Coogan once, and I've worked with Ricky Gervais.
"I had worked with Philip a couple of times before on State of Play and Clocking Off which helped a lot. We just clicked, it was immediate and I was really glad when he got the part. I was so happy.
"I love that partnership that develops between Gene and Sam, it's fantastic and I think Philip is absolutely fantastic."
How did you approach playing Sam? Did you know if he was he in a coma, completely mad or were you playing it as if he really had gone back in time?
"I had to think along the lines of: if it happened to me, what would I do? Sam doesn't know what has happened but Annie's friend, Neil, tells him he's in a coma and so he believes him but Neil is just winding him up.
"However, he hears noises, he hears his mum's voice and doctor's voices, machines beeping so he really believes that he's asleep and he can't wake up.
"But, if he has travelled back in time, he could be in a Back to the Future situation where his actions could have serious repercussions on the future.
"In episode one he is faced with a dilemma where he has the power to change things and he has to seriously think about what he does because it could affect whether his girlfriend in 2006 lives or dies."
He has an interesting relationship with Annie...
"She likes him because he is weird and different and he helps her out and talks to her like a human being instead of slapping her arse when she walks past.
"You can kind of see why she's attracted to that when this weird stranger walks into her life pretending to be from the future and she thinks 'he's a nutter but he's actually really nice to me'.
"Sam flirts with her a little bit. He keeps putting his foot in it; I don't think he's trying to get off with her or anything like that because he's still thinking about his girlfriend in 2006.
"At one point he meets his mum and she's beautiful and younger than him and he quite fancies her and she fancies him. She flirts with him and he flirts with her. That's got to mess with his head!"
Sam meets his dad later in the series. Do you think that you being a father yourself affected how you viewed that whole scenario?
"Yeah definitely, because I can think of how I feel about my son – it affects anything to do with kids that I ever do now. I just get an overwhelming feeling and realise it must have been the same for my dad with me and I realise how he must feel about his dad.
"To get the chance to meet your dad as a young man is a mad thing. Sam is really protective over his dad, he wants to think the best of him even though he left him when he was really young, and he refuses to believe he could be wrong about him.
"It was very strange calling Lee Ingleby 'dad' though. He's about five years younger than me so it felt ridiculous!"
Did the costumes, sets and props bring back memories of the Seventies for you?
I was born in 1970 so my personal memories of the Seventies are a bit vague. I do remember bits of it very well, 1977 for some reason – I remember a specific t-shirt that I wore, which had a Starsky & Hutch yellow transfer on the front.
"I remember the Sex Pistols too - I remember seeing punks. I remember Elvis Prestley dying in 1977 really, really vividly.
"And there were some toys that I had that I remember really well. I had Strika bike rather than a Chopper, it was green and I loved it very much.
"I loved The Six Million Dollar Man; I'm obsessed with Steve Austin. I bought a DVD of it recently and looking at it now, it's absolutely rubbish, I was heart broken!
"I loved Starsky and Hutch, The Professionals and I remember Champion the Wonder Horse, Flash Gordon and Zorro.
"Music holds a lot of memories too, I remember walking into a school hall and hearing Elvis playing, I can see it all now – music does that, brings memories flooding back; music and smells.
"There was a smell from a passport cover the other day and it was literally BANG! It smelt exactly like a toy that I had as a kid, it was exactly the same.
"It was great to go back and rediscover that era. For the first month at least I was looking at all the magazines on set and I think I read every single one of them about twice.
"The pictures of footballers, the big Curly Wurlys, Party Sevens and all that.
"And the cars as well, the array of cars! Everyone on set wanted the Ford Cortina; it became quite a coveted item.
"Screeching car chases, fantastic! Unfortunately I didn't get to drive it because it was Gene's car and I didn't have one which is unfair!
"Hutch from Starsky and Hutch had a car, it was a knackered car but he had a car all the same. Maybe a Capri or something would be nice!
"With the costumes I figured that if this is all in Sam's head then he's not going to want to look completely ridiculous in a clownish suit!
"Luckily because Sam's from the future I didn't have to deal with the big moustaches or long hair or anything like that!
"The suits were outrageously bad so I went for the leather jacket and the Cuban heels which were fantastic. Although it’s hard to chase criminals in Cuban heals I have to say!"