DOUGLAS Henshall saunters into the cafe bar of the Everyman Cinema in Glasgow on a Thursday lunchtime. It's almost seven years since I last sat down to chat with the star of hit BBC Scotland crime drama Shetland.

Back then, in 2012, he was shooting the pilot episode, our interview taking place against the unstarry backdrop of a car park in Irvine, across the road from the now demolished Magnum Leisure Centre.

When I mention it, Henshall looks momentarily stricken. "Is it gone?" he says. "That's terrible. I learned to swim in there. I remember when I was a teenager we used to occasionally go down there to the skating because that is the place you went to maybe meet lassies at the weekend."

He chuckles softly. "But if you couldn't skate, you weren't going to meet anybody, slipping around the edges. One of the first jobs I did out of drama school was a panto at the Magnum."

Having suitably recovered from my accidental bombshell, our conversation turns to his role as everyone's favourite brooding detective inspector Jimmy Perez which will see the 53-year-old actor return to our screens for a fifth series this week.

It has been quite the journey so far. Did Henshall imagine when he embodied Perez for that two-part pilot which aired in 2013 – adapted from the novel Red Bones by crime writer Ann Cleeves – that he would inhabit the character for seven years and counting?

"Obviously, no," he says, wryly. "Because you never know. I thought he was an interesting character and there was possibility. But I didn't think it would last very long in that two-part format. I wasn't particularly interested in doing another cop show that way because it is a pretty dated concept.

"The Scandis blew the crime genre out of the water and the Americans have been doing interesting things with it for years. We had to be brave and follow on with that. I was trying to convince them from the beginning to do six hours on one story."

Testament to that early vision, Shetland has evolved into a six-part series. Previous storylines have shone a spotlight on a miscarriage of justice and laid bare the emotional aftermath of rape, with the latest instalment centring on the hidden brutality of human trafficking.

It opens with a young man inexplicably alone and shivering on a windswept hillside. He is last seen walking towards a vehicle. A few days later, a jogger discovers a severed hand on the beach, while a holdall found at nearby inlet reveals grisly contents: a human head.

Forensic tests confirm that they belong to the same victim, a visitor spotted passing through Lerwick. As Perez and the team scrutinise CCTV, emails and social media accounts, the investigation takes an even darker and more sinister twist.

"People trafficking, refugees and migration is a huge issue in Europe and indeed all over the world at the present moment," says Henshall. "But the ways in which that starts and the abuses that take place during the course of people's journeys has certainly opened my eyes.

"[It has opened them] to the places that can happen and the very insidious ways it happens in places you would never imagine and by seemingly respectable people."

Shetland has always deftly sidestepped the gratuitous violence and so-called "misery porn" that many crime dramas trade on, instead forging its own path through weighty subject matter and thought-provoking themes.

Henshall casts his mind back to series three when Perez's colleague DS Alison "Tosh" McIntosh – played by the brilliant Alison O'Donnell – was raped.

"When I heard that Tosh was going to be raped, I was aghast," he says. "Because I thought, 'Why would we do that?' Ninety percent of the time when you see rape on the television it is gratuitous and there to either bolster viewing figures or as a lazy way of treating female cast.

"Thankfully our show, at that time, was very much headed up by women, which has benefited us hugely. The way in which we approached that – how it was written and carried out – I thought it was much more responsible and the way it should be done.

"A lot of it is down to our writers and the people who produce our show. Then, of course, you have actors and directors who are empathetic and capable of being able to perform things like that."

Tosh didn't feature in Cleeves' books: Perez's bright and ambitious right-hand woman is the brainchild of the show's lead writer David Kane whose past credits include The Field of Blood, Stonemouth, Sea of Souls, Taggart and Rebus.

"Davey Kane is somebody who likes women and I think that comes across," says Henshall. "Everything he has ever written – and I have known Davey for, Christ, over 25 years – he likes women. Tosh is his invention and he has been writing women like that for as long as I have known him.

"There is a great deal of responsibility that goes into the subject matter and how it is explored. It is never for the sake of it because there are too many good bulls*** detectors in our set-up for it to get passed."

Would Henshall call out that kind of thing? "Absolutely," he says, a steely glint in his eye. "Because I am front and centre, I have to be able to stand up and support whatever we do."

He speaks highly of his Shetland co-stars, yet Henshall can be his own worst critic. "I'm not very good at being objective about myself," he admits. "I tend to think: 'What are you doing? Look at you, you big, bleary-eyed, fat f***.'"

Cleeves bid farewell to Perez in her final Shetland novel, Wild Fire, last autumn. I'm fully expecting Henshall to wax lyrical about the character living on within the small screen but he instead throws a curveball. "Yeah, I'm not sure how many more miles it has got," he says. "But we'll see."

The youngest of three children, Henshall grew up in Barrhead and as a teenager joined the Scottish Youth Theatre. His late mother was a nurse while his father, a retired salesman, recently returned to live in Barrhead following several years in Cyprus.

After leaving school, Henshall trained at Mountview Academy of Theatre Arts in London and later did a stint with the 7:84 company in Glasgow.

His first television acting role was as a motorcyclist in Taggart (an episode which also featured Peter Mullan and Ewen Bremner) before going on to parts in Dennis Potter's Lipstick on Your Collar and the films Angels and Insects, Orphans and It's All About Love.

Recent years have brought high-profile roles in the popular time-travelling drama Outlander and playing police detective William Muncie in the ITV mini-series In Plain Sight, about the Lanarkshire serial killer Peter Manuel.

Last year Henshall spent six months opposite Breaking Bad star Bryan Cranston and Downton Abbey's Michelle Dockery in an acclaimed National Theatre production of Network. The actor says that he would happily do a play every year if he could.

There has been a change of scene too. In November, he moved to Glasgow with his wife Tena Stivicic, a Croatian-born playwright and screenwriter, and their two-year-old daughter Anja Grace. Slowly but surely, says Henshall, the trio are settling into their new home in the city's west end.

"I have never lived in Glasgow before," he says. "It is slightly discombobulating because I'm very used to it over the last seven years but not for living here. I lived in London for 30 years, so it is quite odd, but we are in a lovely part of town."

What prompted their move? "Mainly my daughter. We needed to move to somewhere bigger. We couldn't really afford that in London. We could have bought somewhere but I would have been mortgaged up to my neck and probably had a stroke in 10 years. I thought, 'It's not worth it.'

"Then there is the thing with schools in London. We have got pals who are having to go to church on a Sunday just to get their daughter into a decent school – catchment areas are the size of a 10-bob bit.

"There is something to be said for kids growing up in London because if they grow up there, they can go anywhere. But we weren't sure that we wanted her growing up quite that quick.

"We could get a house here that we would never be able to get in London. Our quality of life is going to be an awful lot better. But Glasgow wasn't the only place we were thinking of moving to."

Somewhere more rural, perhaps? "Oh, God no. Coming from London, this feels like I have moved to the country," laughs Henshall. "We were thinking about Glasgow but then, why not Zagreb where Tena is from?

"Then we thought we could maybe go to Los Angeles for a year – my wife and I have both got representation there – but it was Tena who said: 'Let's find somewhere in Glasgow'."

And is she settling in? He nods. "Yeah, but I think she is still in the slight mourning phase for London."

Henshall alludes to his own sense of mourning. "The only thing I really miss since we came up here is the theatre. Because the theatre scene in Glasgow is dead."

Why does he think that is? "The fact that consecutive governments in Scotland still see the arts as a hobby. That is why we are still talking about film studios in Scotland. I have been talking about it for 30 years – and we are still talking about it.

"It is not seen as a viable, money-making, profit-making industry. It is still seen by the people in power as a hobby. And it is a disgrace that people are still that ignorant after this amount of time."

He's warming to his theme now. "The Citizens Theatre in Glasgow used to be one of the most important theatres in Europe. Now it is some wee provincial place. I don't care if anybody is offended by that – that is what it looks like now. It is a disgrace."

Does he envisage that might change after the Citz's £19.4m refurbishment? "No, I don't. Because you have to get an audience in. The great thing that Giles [Havergal], Philip Prowse and Robert David MacDonald did was to make a theatre in Gorbals a community theatre.

"That takes work and imagination. It takes will and a great deal of ambition. You need somebody like that running a theatre who has got an ambition. It is a disgrace and an outrage. It makes me so angry.

"That's where I first started going to the theatre," he continues. "I was 15, sitting up in the gods, getting in for 50p and watching Schiller and all these amazing plays that I would never in a million years have seen. That is what stoked my imagination."

His response is no less impassioned as we move on to talk about the long-mooted plans for a Scottish film and television studio. At the present time, two sites have been earmarked; one in Saltersgate, near Dalkeith in Midlothian, and a second at the Port of Leith.

Does Henshall reckon the idea will ever come to fruition? "It will be a cheap version of it they will claim as a victory," he says. "That preposterous notion of building it on the other side of Edinburgh is just dumb.

"It should either be somewhere practical like Stirling, which is in the centre and you can get everywhere from there, or it should be in Glasgow because you have where all those shipyards used to be. Regenerate that. Because Glasgow could really do with it."

What else does he plan to reacquaint himself with now he's back in Scotland? "The countryside. The food scene in Glasgow is fantastic. Seeing old pals and integrating myself into the city."

Henshall is a fascinating and challenging interviewee: both guarded and gregarious, which makes him tricky to read at times. He has a killer poker face. There are a couple of moments when I fear he's been offended by my line of questioning, only for him to segue into a cheerful anecdote.

As a youngster, Henshall played a lot of tennis and laments the loss of his old childhood stomping ground. "There was a tennis club in the middle of Arthurlie Park and for whatever reason it has been torn down," he says. "That is a travesty given how popular tennis ought to be in Scotland."

An anterior cruciate ligament injury put paid to his own tennis-playing aspirations – "I buggered my knee on a film years ago" – and these days Henshall is into cycling. "I have a road bike – a purist," he says. "It is kind of my midlife crisis, I guess."

To be fair, there are far worse ways to exhibit a midlife crisis. "That's what I said to my wife when I was justifying the amount of money I paid for my bike," he grins. "I said, 'It's not a Ferrari, it's not a Harley-Davidson and it's not an affair with somebody half my age. It is just a bicycle.'"

One bike can become two can become three … "That's the other great thing," he says. "When my wife meets other people, who have six or seven bicycles, I'm like, 'I have one …'" For now? "One is fine. Although we have got room in our house now, so I could, but I think she might shoot me."

He clearly craves the outdoors life, something Henshall hopes his daughter will share. "Now we have moved up here there will be a lot more scope for getting out in the country for walks," he says. "The bigger she gets I'm sure she will love that. I want her to be an 'outside' person."

Henshall is reticent on what work projects he has in the pipeline. "There is a couple of interesting things kicking about but I don't want to talk about them because I don't want to curse them," he says.

What about burning ambitions? "I would like to work in America. But I am past that overly ambitious phase of my life. I would like to stay as relevant as I possibly can as an actor.

"I want to keep working on things that are going to push me and are intellectually interesting with subject matter that is relevant and exciting. Mainly, I like working with good writers."

He isn't a man to turn up, deliver his lines, take the pay cheque and go home. Henshall looks pained at the suggestion.

"Och, no. I could have had a much easier life if I had decided that is what I wanted to do with my work," he says. "But I never have. I don't really see the point in changing now."

Shetland begins on BBC One, Tuesday, 9pm

Thanks to the Everyman Cinema Glasgow (