Joe McFadden is terribly nice: warm, modest and apparently incapable of saying a bad word about anyone or anything.

Despite beginning his acting career at a precociously young age, the 36-year-old retains a sense of wide-eyed wonder that he’s being paid to spend his days like this.

He’s currently starring in Alan Ayckbourne’s psychological thriller Haunting Julia, where he’s on stage for the two-hour duration. “It’s quite demanding. You get on the treadmill and you’re off. But it’s fun; it’s acting. People do much harder things.”

He plays the ex-boyfriend of Julia, whose death in mysterious circumstances has had a profound effect on her father (Surgical Spirit’s Duncan Preston), who brings in a medium to help him contact his daughter. “It’s sometimes described as a ghost story but more than anything it’s a study of grief and lost love, and I think that makes it more interesting.”

For a while, McFadden seemed pegged as a TV actor; in his native Glasgow, he’s still most often recognised for Take The High Road, a soap he appeared in for several years (“It’s kind of annoying”), while in the South, it tends to be for Heartbeat, the cosy, 1960sset Sunday night drama in which he played motorbikeriding PC Joe Mason until the show was axed in 2009.

But in the past few years he’s done very little TV, instead appearing in a collection of wellreceived theatre, from Andrew O’Hagan’s hard-hitting drama The Missing, through playing Aladdin to Sir Ian McKellen’s Widow Twankey, to the Torch Song Trilogy at London’s Menier Chocolate Factory earlier this year.

It was theatre that “demystified” acting for the self-taught actor. On the recommendation of a beloved secondary school drama teacher (“She still sends me Christmas and birthday cards”), McFadden made his debut in Taggart at the age of 12, before moving on to a six-year stint in The High Road at the age of 15.

He’s rarely been out of work since and his CV also includes TV’s The Crow Road, Sex, Chips And Rock ’n’ Roll and 1996 coming-ofage film Small Faces.

But he felt at a disadvantage not having studied his craft.

“At the beginning, I was quite bothered at not having gone to drama school and I really felt the absence of it for quite a while – just trying to imagine what everyone did for three years, as much as anything!

Then I started doing plays and it sort of demystified it all. It reminded me that everyone’s making it up and there are no hard and fast rules to it.”

Despite his early success, he insists he had a relatively normal upbringing. “I don’t feel I lost out on my childhood or anything. I think it was quite good for me to learn discipline from that age and I do feel a bit like… not that acting rescued me as such but that it was a good thing to do.

“I was very introverted as a child and you find that with a lot of actors – we seem to like playing make-believe because it gets us away from ourselves.

It certainly brought me out of my shell.”

The son of a working-class Glaswegian builder, McFadden was an unlikely candidate for showbusiness. He says his family are still rather baffled by what he does. It perhaps explains why he steers clear of any self-aggrandisement.

“It’s just playing,” he shrugs of his work. “And you don’t have to get up till 11, which is a relief for a vampire like me. The 6am starts on the building site would have done me in!”

He describes most of his roles as “lovely”, particularly Cranford, where he got to hang out with both Judi Dench and Imelda Staunton.

“I was star-struck, absolutely.

I was the only person on set I’d never heard of. But I find the big stars are, for the most part, really lovely. They have nothing to prove. It’s the ones who want to be more famous you have to watch out for.

“I just had a really lovely time on Cranford. There was such a nice atmosphere on set.

I remember thinking even if didn’t become the massive success it did, it was still a great job to do.”

All this niceness may come across as diplomacy but it seems genuine. As McFadden points out, he’s no wild man.

While it’s tempting to imagine the cast of Heartbeat secretly leading lives of excess, he says behaving well off-screen came naturally to him.

“We didn’t have time for all-night binges even if we’d wanted to, not with those early calls. But it’s not something that appeals to me much anyway. I tend to have a lot of early nights, boringly.”

It’s no coincidence, then, that McFadden is not among the TV stars who find themselves splashed across newspaper gossip pages of a Monday morning.

“I try to avoid talking too much about personal stuff.

I think you need to keep an air of mystery as an actor. If people know too much about you, it’s more difficult to convince them you’re someone else and I knew from quite a young age that [excessive publicity] wasn’t a road I wanted to go down as it can turn round and bite you.”

He even worried about taking the Heartbeat role for fear of becoming public property. “I have an actor friend who’d been in Corrie and she told me the press would hound me, go through my bins and all that. But of course Heartbeat fans don’t read the red tops, they don’t want to know the latest scandals – well, there aren’t any! But I think soaps can be a bit of a poisoned chalice in terms of your personal life.”

One gets the impression McFadden is not in the habit of chasing fame. He said a few years ago he thought it was unlikely he’d become a movie star, despite watching co-stars from Small Faces go on to appear in shows including Grey’s Anatomy and Breaking Bad.

“It seems like hard graft going out [to the States] and doing the rounds of studios again. I feel things are going well for me over here and I’d be mad to turn my back on that.”

He seems bemused by the common assumption an actor would automatically want to be a film star. “It makes me feel I’ve let people down somehow but I just enjoy doing what I am doing – great plays and dramas with interesting people. I don’t think there’s anything strange about that!”

*Haunting Julia is at Theatre Royal Brighton from Tuesday, December 4 to Saturday, December 8. For tickets, call 0844 8717627.