Shaun Evans’s Endeavour Morse is a winningly decent man prone to drinking good bitter, watching tragic opera, solving crimes and — at least over the course of the 27 films broadcast so far — never finding love. In short, and rather pleasingly, he’s pretty much exactly like the older version played by John Thaw in Morse.

Both series are premier ITV shows, classy whodunnits steeped in elegiac wistfulness. Yes, the narrative is driven by the search for who bumped off whom, but over the eight years Endeavour has been on air, there has been an intriguing narrative thread examining police corruption and Masonic penetration in the (fictional) Oxfordshire police of the time. Whatever happens we can take comfort from the knowledge that if there’s one good man, it’s young Morse, even if he’s not always easy to understand.

So far we have followed him alongside his boss and father figure, Roger Allam’s no-nonsense DCI Fred Thursday, for most of the 1960s; the new seventh series starts on New Year’s Eve 1969 on the cusp of the grim 1970s. It has been slow progress towards an inevitable end. In 2000 John Thaw’s Morse had a fatal heart attack in the quad of an Oxford college, dying in hospital after cracking his last case in an episode called The Remorseful Day.

Young and old, Morse famously won’t let people into his heart and life. And when it comes to Evans, the bright Liverpudlian who stars as his youthful iteration, it’s all too tempting to draw parallels between the policeman and the actor who plays him.

He is certainly thoughtful and understated when we meet in a quiet room at the ITV headquarters. And boy, does he try not to let you in; I lost count of the times he stood up to pad around when he found a question tricky, often pausing to lean against the wall and look skywards.

“Oh my God, 45 minutes,” he says with a pained smile when I tell him how much time we have. “Intense.”

It’s hard to imagine a person less keen on giving interviews. Why is that?

“I think two things.” He pauses before continuing. “The likelihood of me divulging something to someone I don’t know is very slim, right? It’s not the kind of person I am. The second thing about it is the more people know about you the less willing they are to align with you as an actor when you play a part. And the work is enough for me; it’s its own reward. I don’t need…” He pauses again. “The bollocks that comes along with it can be distracting to your work and it’s that that I am quite guarded against.” Nice to meet you too.

Evans is reluctant to even confirm certain details about his early life, although he doesn’t contradict me when I say I understand that his dad worked as a taxi driver and his mum as a hospital care worker. “It was me who chose to go into this job, neither of them did,” he remarks, not unreasonably. “So it would be unfair.”

Evans, 39, seems to have had a settled early life, winning a place in the sought-after state school St Edward’s College on the outskirts of Liverpool. He acted in school and proceeded happily though the National Youth Theatre, eventually enrolling at the Guildhall School of Music and Drama and getting his acting break as the French teacher John Paul Keating in the Channel 4 comedy-drama Teachers in 2002.

He seems proud of his home town, rather sweetly calling Liverpool “the pool of life”. So did he, I ask, have a happy childhood? “F*** off! Of course it was happy,” he says, flashing the kind of huge smile the Big Bad Wolf gave Little Red Riding Hood.

I don’t mention his four-year romance with the pop star Andrea Corr, which is the only relationship of his that we know about (it ended about 2006). I have been warned off personal questions in advance and his manner suggests that I would be wise to follow that stricture.

He’s a handsome man, I tell him, which draws a friendly smile. I lightheartedly add that there’s a sizeable contingent of mums at my daughter’s primary school who find him desirable. Another silence. I am starting to explain that if you google “Shaun Evans” the first sentence that comes up is “is he married?” but he interrupts before I can finish the sentence. “Don’t even tell me,” he says, with an agonised laugh.

He doesn’t read interviews or critics and says he probably won’t read this piece.

He wants, he keeps reminding me, to talk about the work; something he takes so seriously that he has started directing episodes as well (he directs the opening episode of the new series and did one for the previous series).

“Ultimately, I am the judge of my own work; I know that sounds very grand. To be honest I try not to intellectualise because the work is more interesting if I don’t. You try to be as instinctual as possible… I ask the opinions of the people I respect.”

In the previous series, pre-publicity pictures of his character’s new moustache went viral. It sounds like the kind of thing that would have irritated him, but he claims that wasn’t the case and says that the facial furniture (which is gone for the forthcoming series) wasn’t a piece of frivolity denoting the move towards the 1970s. No, it was modelled on the one sported by August Strindberg, that dourest of playwrights.

In any case, the new three-episode series is determined not to play to stereotypes and preconceptions about the grubby, grimy, strike-ridden, sexually careless, slightly corrupt, mustachioed 1970s. He describes the episodes as having an “operatic” acts structure, in keeping with the musical passions of its hero.

Evans is more revealing when he talks about politics, an inevitable area of discussion given we meet the day before polling stations open for the December general election. Before he decided to become an actor, he had considered studying history and politics at university, and he still takes a keen interest in the subject.

He’s not a Tory, he says, “not a fan” of Boris Johnson and is unhappy with the way the world is run. “It’s not just the US; it’s something that’s also worldwide. [But] things are happening. Younger people are getting involved and having more of a say.”

One suspects he was a Corbyn fan and voter (although he won’t say where he is planning to land his cross) and in hindsight there is something rather poignant about his optimism before the Labour wipeout that came to pass. “I think something wonderful IS about to happen,” he says. (Unless he really is a Tory.)

There is at least one journalist he does admire. “Emma Barnett is f***ing brilliant, isn’t she?” he says. “She’s so impressive, funny but also direct. I think she does a great job.”

As for his plans for Endeavour, he can’t promise another series next year, insisting it is commissioned on a year-by-year basis, and suggests that there could be an end in sight. As with the departure of Corbyn, though, it’s not happening straight away. The writer Russell Lewis (another man not keen on giving much away in interviews) said last year that he has a planned end in mind — “there is a terminus, our own Remorseful Day” — and confirmed he won’t take Morse into the 1980s (the decade when we first met Thaw’s Morse, in 1987).

And what does Evans think? “We’ve come this far down the road and I want to finish it in a way that’s decisive and does it justice,” he says.

But fans of Morse’s immediate boss, the beautifully dour and decent Thursday, may need to shut their ears. Fans have always noticed that Thursday is not referenced in Colin Dexter’s Morse stories, but DS Strange — played by James Grout in Inspector Morse and Sean Rigby in Endeavour — is. The creators of Endeavour clearly have something up their sleeve for Thursday, a man whose decency was compromised by his flirtation with the Freemasons in earlier episodes. Before the series draws to a close, is the great man going to do something so terrible and disillusioning that older Morse never speaks his name again?

“Oh, it’s gotta be!” says Evans. “Haven’t you been paying attention? Dramatically it’s got to be something bad.”

Well, I have been paying attention, I want to answer. It’s why I asked the question. But I don’t.

Evans hopes to continue directing and slightly balks when I ask if he could do that full-time. “Why can’t you do both?” he says, which is also a fair point. His eyes light up when I ask him about his photography work. You get a real glimpse of the passionate and likeable man that people who work with him constantly describe.

“I’m a photographer on the sly. Black and white, mainly. I’ve been taking pictures since I was 15. The first job I ever had was in a camera shop when I was 16 and the first proper camera I bought was when I was 20. I just do it for myself. If people like it, that’s cool.”

He seems reluctant to even say what his subjects are. “They’re people… not portraits,” after another long pause. “It’s another manifestation of telling stories. My hope with it is that they are enigmatic images that draw you in and, when placed in a sequence, can tell a narrative that perhaps wasn’t there at the beginning.”

So even his hobby is enigmatic. Now why is that not a surprise?