Prime Suspect 1973's Blake Harrison: 'I can't say how it will compare to original. But what the show does quite nicely is it doesn't throw the sexism in your face'

Neil from 'The Inbetweeners' grows a moustache and gets serious as DS Spencer Gibbs in ITV's 'Prime Suspect 1973', an adaptation of Lynda La Plante's prequel novel, with a new Jane Tennison

PC brigade: Blake Harrison as DS Spencer Gibbs in ITV's 'Prime Suspect 1973'

“I've not got the most attractive face in the world, so I cover it with hair”, says Blake Harrison with unexpected candour when I ask him about his beard. I had been wondering about the psychology of his chin-curtain, whether he had grown it as part of his long-standing effort to distance himself from the character of Neil, the gormless but big-hearted member of the sixth-form friends in E4's The Inbetweeners – “the cockney idiot”, as Harrison calls him. “No, I've always had a beard”, he says.

Except he doesn't in Prime Suspect 1973, ITV's new adaptation of Lynda La Plante's prequel for her most famous character (the one played by Helen Mirren in the original TV adaptation two decades ago), Jane Tennison. But he does have a moustache – a semi-zapata favoured by the more dandified blokes of the era. In the drama, in which Stefanie Martini plays the 22-year-old rookie WPC Tennison, Harrison is one of her senior officers, DS Spencer Gibbs, to whom are introduced while he admires Tennison's behind. “Gibbs is eyeing her up as a potential conquest”, says Harrison. “WPCs were quite new in the police force back then.”

“Back then”, as the title states, is 1973 – the same year as depicted in the BBC time-travel cop-show Life on Mars. It's a lot to live up to for a fledgling TV drama, arriving in the shadow not only of Mirren's Prime Suspect, a television classic that went on to inspire (I have personally been told by a couple of Nordic writers) the whole Scandi-noir crime genre, but also Ashley Pharoah's 2006 retro-fantasy that wittily explored the social attitudes of the 1970s. “I can't say how it will compare to original”, remarks Harrison. “But what the show does quite nicely is that it doesn't throw the sexism in your face, it's all the little things that build. So if Jane is washing her own plate after lunch, someone will come in a drop their plate and say “Be a love...”. And whenever there's cleaning to do in the office, if a junkie's thrown-up, despite having 50-odd male officers to choose from, it's one of the women.

Blake Harrison's role in 'Prime Suspect 1973' is a chance for him to prove himself as a straight actor (Rex)

“There are stories of WPCs carrying trays of teas down to senior officers and men would just come up behind them and grab their boobs and think of it as just a joke. But what was amazing was that the attitude of the WPCs wasn't ‘I've been sexually assaulted... that's disgusting', it was 'you could have made me drop the teas, you idiot!'”.

For Harrison, the role is a chance to prove himself as a straight actor after three series and two hugely successful feature films playing Neil in The Inbetweeners. And it was this desire to avoid pigeonholing that initially made him hesitant about accepting the role of Private Pike in last year's big-screen version of Dad's Army. “If that had been a different cast, I wouldn't have done it”, he says. “That's the closest role I've done to Neil since The Inbetweeners, and it was going to be another high-profile one, so was this a good move when I want to actively pursue drama? But for me it was a case of 'how can I turn down the opportunity to work with Michael Gambon, Tom Courtney, Bill Nighy and Catherine Zeta Jones?’.”

Harrison was born in 1985 in Peckham, south London, home of Del Boy Trotter in Only Fools and Horses, but these days yet another hitherto unlikely part of the capital undergoing gentrification. “Mate, go back there 25 years ago and it wasn't trendy, hipster Peckham,” recalls Harrison. “I've got mates who've moved to Peckham and I couldn't wait to get out of Peckham. We were burgled when I was about a year old, and we used to play football round our estate where the metal bins were and there were like drug addicts shooting up.”

'Prime Suspect 1973': Tommy McDonnnell as DC Ashton, Sam Reid as DCI Len Bradfield, Stefanie Martini as Jane Tennison, Harrison as DS Spencer Giggs and Joshua Hill as DC Edwards. (ITV)

His father is a former cabbie who now works for the government car service (“driving MPs around”), while his mother works in the administrative department at Goldsmiths University. It was Harrison's mum who did all the ferrying to and from drama classes – first on Saturdays at the Sylvia Young Theatre School and then, from the age of 14, at the BRIT School in Croydon, alma mater of Adele, Leona Lewis and Amy Winehouse. “It never wavered,” Harrison says of his acting ambition. “I'm one of those lucky people who knew from an early age what I wanted to do.”

All the same, he lucked out when he went more or less straight from drama school into an open casting call for a new E4 sitcom called Baggy Trousers (soon to be re-named The Inbetweeners) – again with a little help from his mum. “I had just got a job at a call-centre,” he recalls. “And I'd done one day of training when I got a phone call saying 'will you come in tomorrow for an audition for this thing?'. I was thinking I might not go, as I might have to start my training again. And my mum was like 'what are you talking about? You've been to drama school for three years getting into debt... you're an actor, just go and do it'”.

The Inbetweeners wasn't an instant hit – and after the first series Harrison got a job at Madame Tussaud's (“In the Chamber of Horrors... I loved it”) – but by series two they knew they had a phenomenon on their hands. “We had a young cast and everyone was hungry to do a good job”, he says of his co-stars Simon Bird, Joe Thomas and James Buckley, and disappointing those who might think that the cast got up to any of the same antics as their characters. “It's never what people expected,” he says. “They expected us to go out and get smashed and try and pull girls and do something stupid. But we've never been that way, we've been quite reserved and if we have gone out together it's been for a couple of glasses of wine and a nice meal.

The Inbetweeners Movie: Joe Thomas as Simon, Harrison as Neil, James Buckley as Jay and Simon Bird as Will

“When we were in Magaluf doing the first film, we were asked to come to the local super-club and have a free night out. And we all just looked at each other and said we could not think of anything worse. We ended up going going into Palma and having nice tapas, and we found a wine-tasting place... that was our idea of fun.”

These days when the cast meet up, he says, it's more likely to be for play dates with their various children – Harrison and his wife Kerry, a former stage manager and theatre PR, having a three-year-old daughter, Autumn. They first hooked up in circumstances that sounds pure Inbetweeners, on a pub crawl where Harrison joined Karry and her friends while they were playing a game of 'Mingers Top Trumps'. “We kept on locking eyes, but I'm rubbish at talking to girls”, he says. “I was obviously lingering and she invited me to play, and a bunch of terrible jokes later she gave me her number, and that was over seven years ago.”

They live in Kent, but not the plush, mortgage-free existence some might expect after the extraordinary box-office success of the two Inbetweeners movies, which raked in nearly £100m worldwide – an enormous return on a relatively modest budget. “People think that because the movie made lots of money, we made lots of money, and I can tell you now, it's 100 per cent not true,” says Harrison. “On the second movie, we had a lawyer explain to us the ins and outs of movie finances, and there was a lot of stuff went over my head, but basically movie finances don't work the way you think they do.


 Stupid boy: Harrison (far left) as Pike in the 2016 ‘Dad's Army’ 
 (PA)

“Don't get me wrong, I've done well for myself. But I'm not splashing money around, because I know there might be a time when I don't work for five years. But at the moment I'm comfortable in knowing that things are covered and I can turn down work you don't want. And I want to pursue drama roles.”

To that end, Harrison is now on his way to Scotland to film a psychological drama for the BBC, Trust Me, co-starring with Broadchurch's Jodie Whittaker. And then there will perhaps be time to complete his honeymoon with Kerry – their beach-wedding in Mauritius having been cut short when Harrison was cast in Prime Suspect 1973. “I got the phone-call for this job the day before flying out to Mauritius,” he says. “I was thrashing out my deal Saturday morning at Gatwick airport. We were supposed to have two weeks and I ended up having just one – I had to leave my new wife and daughter and family and friends who had paid money to come out to Mauritius. We got the wedding in, obviously.”

'Prime Suspect 1973' begins at 9pm on ITV on Thursday 2 March