TAM Dean Burn conjures up a very close approximation of evil when required in TV roles such as the gangster McCabe in BBC Scotland’s River City or rapist Billy Pettigrew in the Sky drama Fortitude. And he’s not afraid to reveal a delightful borderline madness either, as evidenced on stage by his Mad Hatter.

Yet away from performance the man is a bigger sweetie than a packet of fruit pastilles. What’s intriguing about the Leith-born actor is how he so readily accesses this entirely convincing darkness. How can someone, as he did, play out a rape scene in Fortitude yet hours later find himself telling children about the Gruffalo?

And if actors have to call upon certain experiences to transmit the worst of feelings, I wonder what sort of trauma has he endured, what form of soul-corroding cesspit has he had to crawl out of to give him his starting position in the likes of Trainspotting, where he voiced the audiobook?

“I had a really happy life growing up Clermiston, this council estate above Edinburgh Zoo,” he recalls over coffee in a Glasgow hotel. “It was like being in the country. We had woods and fields all around and we could climb the fence into the zoo at night. There was such a strong sense of community my parents didn’t want to leave that house.”

Burn’s father was a joiner whose sons Tam, Russell and Philip went on to represent a council house success story. “My ma used to love Art Sutter on Radio Scotland and she would call him up on air. One day she got through and Art said, ‘Jean, you have three sons, what do they do?’ She didn’t want to say, ‘One’s an actor, one’s a professional footballer and the other is a musician.’ She figured nobody would believe her. So what she said was, ‘They’re all doing their own thing, Art.’” Burn laughs. “He was probably thinking we were drug addicts or in prison.”

But where was the angst, Tam? The most demanding part of early life seems to have been which books to pick at the school prizegiving. Was Clermiston that close to Walton’s Mountain?

“Not quite,” he says. “Growing up there was great but at 18 I was desperate to get away from home, given us three boys were in the one bedroom. But my ma and da wouldn’t move out of the area. It was driving me demented until an actor pal offered me a room in a flat.”

When the eldest Burn announced he was for the off it caused great consternation. “It was a nightmare,” he says with a rueful shake of the head. “I was the first person in my extended family to move out of the house without being married. My ma was black affronted.”

Burn wasn’t the cliche child actor, desperate to perform. “I did the gang shows when in the Cubs, though. And my ma loved getting me dressed up to go guising. I remember going round the doors wearing a Girl Guide uniform with bloomers on. And she had me in a kilt when I was young, singing A Scottish Soldier.

“But I only became interested in acting at Craigmount High. We had a great theatre space and drama teachers in Joyce Heller and Ken Morley [who would go on to become a Coronation Street favourite, as Reg Holdsworth].”

Yet Burn’s good grades mitigated against developing his love for acting. “Because I was set to do O-levels and Highers I couldn’t do drama any more. That was it. Gone.”

It didn’t matter too much. The teenager planned to become a journalist, yet fell at the first hurdle. “The closest I got was the short list for a traineeship at the Scotsman,” he recalls and adds. “It’s as well I didn’t get in. I would have become an alcoholic. That was the world at the time.”

Instead he formed a punk band, the Dirty Reds, and forgot

about journalism because he couldn’t take the rejection, he says, so it seems strange he signed up to be an actor. “Yes, but as an actor you get chosen, which gives you validation.”

Burn’s thoughts turned to professional acting when he saw an advert for actors in the paper. He wanted to be the Scottish James Dean. “I didn’t have the hairstyle, though,” he says, smoothing his shiny head. Regardless, Burn took himself off to drama college then worked as an assistant stage manager at Perth Rep, the perfect vehicle for a budding actor. Or so you would think.

“I know, it sounds odd,” he says, with a wry smile, “but to be honest, I nearly walked away from acting after a few months. We were doing a series of Agatha Christie plays and I complained, ‘Ah cannae take this any mair.’

"But the bloke who hired me said, ‘If you leave you won’t work in Scottish theatre again. Your Equity card will be ripped up and you’ll be in Joan Knight’s [the boss] little black book.’ So I thought I’d stick it out. But it wasn’t me at the time. I was a punk.”

Burn was 30 – he’s now 59 – before he accepted his role in life as an actor. It had all seemed too middle class. But then he realised acting didn’t have to be about solving mysteries in large period houses and went on to perform work that helped feed his need for a sense of community. He enjoyed stints with the likes of TAG Theatre Company, based at the Citizens Theatre in Glasgow, and he performed everything from Steven Berkoff plays to schools productions. Now he felt at home.

Yet, where was the angst coming from which emerged in his performances? “There certainly was an anger,” he admits. “I did have a temper, which fortunately I could let loose on stage.” Part of the anger was directed at politicians. In 1990, Burn stood for Glasgow Central on the Communist Party of Great Britain ticket. (He managed to achieve triple figures.) “It’s hard to say where the politics came from,” he says, assuming the obvious question. “I guess I always had a sense of injustice.”

As a boy he loved reading the Jennings series of novels, the tiny toff’s school adventures by Anthony Buckeridge. “It may sound strange but Buckeridge’s obit revealed he was a socialist, so perhaps his thinking came across in his writing. It’s the only thing I can guess.

“Later on I had a very romantic idea of the Soviet Union. I had once been in the prison Trotsky had been banged up in. I knew there was so much wrong with the Soviet Union but I wasn’t going to throw my lot in with those who were so anti-Soviet.”

These days Burn is a Labour man, invigorated by Corbyn. His outlook on acting has evolved too. “There is a big part of me that’s a real loner,” he admits, “yet I love to be part of a team, doing good work.”

In recent years he toured Scotland on a bicycle, reading all 195 of Julia Donaldson’s Gruffalo stories to children. “I don’t like the world of actors blethering. I like the idea of developing the craft, finding things that matter, in the wider political sense such as the Children’s Wood in North Kelvin Meadow," he says, referring to the Glasgow community site which was under threat from a housing development.

The notion of putting something back via community work clearly soothes his spirit. Yet, every now and then, Burn gets the chance to appear on stage or on film and let loose with the madness, to reveal the dark, quirky character, as in the case of new film Moon Dogs. The story follows teenage step-brothers Michael (Jack Parry-Jones) and Thor (Christy O’Donnell) as they journey from Shetland to Glasgow for very different reasons. Aspiring Irish singer Caitlin (Tara Lee) beguiles both boys and passions come to a head at a music festival.

“It’s a lovely wee film and I’ve got a nice part as a sleazy folk promoter who’s also in charge of a fish factory.”

It’s not just anger that emerges in Burn’s performances. It’s raw emotion. The actor once said, “I bruise a bit too easily.” Does this suggest a darkness he has to work at containing?

“Oh, yes,” he agrees. “I’ve never tumbled into full-blown depression but I am a needy f*****. I also have a high metabolism, so I need to work at remaining calm. That’s why I set a lot of store by meditation, which I do every morning, and I’m into Tai Chi.”

Burn speaks of great losses in his life, and although he says he has accepted them his vivid descriptions suggest emotions could well up at any moment. “My ma [who had cancer] was in St Columba's Hospice when she died. I sat and held her hand and talked to her and sang to her throughout the night and watched her breathing. I went for breakfast, came back, and then it was as if she had held off because right then her breathing stopped. There was a joy in this type of release. And thankfully my dad [who had dementia] was released before he lost all his dignity. We sang Neil Diamond songs with him before he died.”

He speaks of how the three Burn boys are now two after his brother Philip, who played for Raith Rovers, became "a professional alcoholic".

"He was a brilliant lad, not a bad drunk, but he loved the effect of drink. He had become so toxic he died in his sleep, aged 43. That finished my mother off.”

Burn shares his losses without seeking sympathy. He’s simply explaining his life. And now he’s certainly in a happy place. He and his partner Emma, a press manager, have a seven year-old daughter, Morgan, whom Burn dotes on. (He has a 30-year-old son, Skye, from a previous relationship.)

The actor is working on several projects, including a bio-play based on the life of Pinkerton, the Scot who founded the US detective agency. “I love to write every day,” he says. “It keeps the muscle working.”

What I sense of Tam Dean Burn is a man who has had to work to battle demons. Yet I suspect the demons are the result of over-questioning, self-reflection, worry and doubt. “I’ve got a lot of energy and a lot of frustrations so acting does offer an opportunity to let it all out. I’m quite a shy person, really.”

He has no need to be famous, but he wants to be wanted. “I was up for a big movie recently and very nearly got it. And it’s hard for an actor to take that rejection.

“I could plumb the depths which meant I’ve been an emotional rollercoaster, and this could be hard for anyone associated with me. But I’m gentler now. I’m not so up and down and not so desperate.”

Yet he can bring the big emotions to the surface when required. “Sometimes directors have to pull me back,” he admits. “I once went up for an ad with Ken Russell for frozen food where I had to get up and sing Food, Glorious Food. So I did this and he yelled out, ‘Bit OTT, darling!’

"I had to laugh that Ken Russell reckoned I had gone too far.”

Moon Dogs (15) is out on September 1