By his own admission, Rory McCann is a big man, and he's struggling to adjust to the heat of Santa Monica. The towering Scot who plays Sandor "the Hound" Clegane – foremost sword-swinging badass in a series not lacking on that front – is in LA for a Game Of Thrones premiere and goblet-clanging celebratory shindig, along with 23 other stars from the show. "So about 20% of the cast," he chuckles.

The ever-expanding character list of HBO's blood-spattered epic has become a running joke: season three adds Diana Rigg, Paul Kaye, Mackenzie Crook and more to the pool of Britain's GoT talent. But in Westeros, the medieval-ish land of fleshpot diplomacy and lethal realpolitik described in George RR Martin's fantasy doorstops, there's a high degree of natural wastage. Just ask Sean Bean.

The Hound has done his part to keep the population down, cleaving folk in twain with grim efficiency. With his Freddy Krueger face and disagreeable fealty to a callow king, Clegane should be a clear-cut baddie, someone to hate just as much as spiteful nyaff Joffrey. But under all the scars and muck, there's a soulfulness to McCann's performance. Whenever the Hound edged towards heroism – like saving young Sansa Stark from sexual assault – it sparked off a new round of breathless fan fiction. And when, at the end of season two, he memorably resigned from the post of royal bodyguard – "Fuck the king," he muttered – everyone was suddenly on Team Hound.

So, newly unleashed, where is Clegane's head at for season three? "By disrespecting Joffrey publicly, he really signed his own death warrant," sighs McCann. "He's essentially an outlaw." In the simplified economy of Westeros, surely his deadly skillset would make him attractive to potential employers, even without a reference? "There's probably not many people who can overpower the Hound," he admits. "But he's got issues, he's the product of a brutal past. He needs therapy. Or maybe he just needs a cuddle." A hug looks unlikely: McCann is something of a hulk already and trained for over three weeks for a one-on-one fight scene in Season Three that he claims will change the Hound forever.

The idea of the Hound as a wandering ronin echoes McCann's unconventional lifestyle. He's accumulated a collection of swords and armour from his various roles in historical and fantasy movies such as Solomon Kane and Clash Of The Titans, but doesn't have anywhere to display them. "Home for me is my boat, really," he says. (It's currently moored in the Highland region of Wester Ross, a place that inspired the young George RR Martin.)

'I was a bit of a late developer … I remember rubbing the soot from a kettle on to my bumfluff to make it look more like I had a beard'

Rory McCann hits the red carpet for the Game Of Thrones season three premiere in Santa Monica. Photograph: Rex

McCann's first acting gig was 25 years ago, when he stumbled across an open casting call for Ron Howard's Willow while hitchhiking in Wales. Soon he was standing next to the legendary Pat "Bomber" Roach in a quarry trying to look like a fearsome warrior. "I was a bit of a late developer and everyone was saying, 'Whatever you do, don't shave,'" he recalls, "and I hadn't really started shaving. I remember rubbing the soot from a kettle on to my bumfluff to make it look more like I had a beard."

In his time, McCann has also worked as a painter on the Forth road bridge and – just before booking his Game Of Thrones audition – he was lumberjacking, an axe-swinging furlough that seems pretty appropriate. He regularly misplaces his mobile phone – "Although no one seems to mind," he says – and while he's taking a series of meetings in the US, he sounds more excited about getting back to his boat. "I'm in the process of replacing all the rigging, so soon I'll be able to get out there and do some real high-seas sailing."

The Game Of Thrones books are subtitled A Song Of Fire And Ice, and more music is creeping into the TV version. McCann approves of a bawdy drinking song recorded by the Hold Steady, and there are grubby cameos from Gary Lightbody of Snow Patrol and Will Champion of Coldplay. Dr Feelgood guitarist Wilko Johnson, recently diagnosed with pancreatic cancer, also reprises his role as an executioner, although he offered the Hound axe advice of a different kind. "I'm just looking over at the guitar I take with me when I'm travelling," says McCann. "Wilko signed it and gave me a couple of lessons, told me never to use a plectrum and just bash it till my fingers bled. I swear to God he put magic dust in that guitar. Just by him touching it, I'm sure I got 15% better. He's an incredible guy."

But what about the Hound? Under the scowl, does he have an untapped musical side? "He's not just a loner sitting in the corner looking grumpy all the time," says McCann. "I can see the Hound maybe rattling up a song when he's absolutely upside-down with drink. I'm not saying he's at the piano or playing the ukulele, but I'm sure in the right situation he'd be giving it laldy."



Game Of Thrones returns on Sky Atlantic in the UK on Monday at 9pm and on HBO in the US on Sunday at 9pm ET