From rural Worcestershire to Westeros, why the raven-haired Game of Thrones actor has Hollywood at his beck and call.

Meeting a famous person in the flesh typically requires a lightning-fast adjustment of expectation. In the case of Mr Kit Harington, the break-out star of the global TV smash Game of Thrones, this distorting effect is both reduced and, oddly, magnified. He looks exactly like Jon Snow, the hero he plays on the show – same tangled raven locks, same close-cropped beard, same pensive expression. So that’s reassuring. All the more jarring, then, that rather than Snow’s familiar fur-collared cloak, Mr Harington is wearing a summer blazer, and instead of wielding a broadsword, he’s carrying nothing more immediately threatening than a pack of Marlboros.

In other words, he is both instantly recognisable as the brooding, saturnine Snow, and apparently nothing like him whatsoever: a chatty, unassuming Englishman, 28 years old, with the entertainment world at his feet, who just happens to look uncannily like a mythical warrior of Westeros. It’s a little disorienting for me, so imagine how he feels.

“I think the moment I realised [Game of Thrones] could be a life-changer personally was going to Comic-Con for the first time,” he says. “I’d splashed out on a drop-top Mustang in LA, and I drove with my girlfriend at the time to San Diego. I got out of the car and… flashbulbs!”

I am dimly aware, of course, that outside Comic-Con there are those who come to Mr Harington with no preconceptions at all. People for whom Game of Thrones, the HBO megahit based on Mr George RR Martin’s fantasy book cycle, is just another box set they haven’t bothered to download – like The Newsroom, only with dragons. For the purposes of this article, those people need know only this. Game of Thrones is set for the most part in the aforementioned continent of Westeros. In the far north is a high wall, defending those to the south of it from the terrifying spirits on the other side. This wall is guarded by the Night’s Watch, an un-elite organisation consisting of, as one character describes them, “sullen peasants, debtors, poachers, rapers, thieves and bastards”. Jon Snow is the latter – the illegitimate son of a nobleman. His scenes are almost all played out at the wall or in the wilderness beyond it, far from the main action. Mr Harington has now completed five seasons – the fifth is showing now – and later this year, as long as his character survives (he’s not telling but I think we can make a safe bet, based on the fact he’s still wearing the hair), he’ll be back in Northern Ireland for the filming of the sixth.

Unlike other prominent cast members, who play more flamboyant figures, Mr Harington does not get to chew much CGI.

“He’s incredibly introverted,” says Mr Harington of Snow, over a companionable cup of tea in the kitchen of the house in south London where he’s been posing for MR PORTER. “It’s like if anyone in Game of Thrones didn’t want to be on the show Game of Thrones, it’d be Jon Snow. If he could see the cameras, he wouldn’t want them there. He lives in his head.”

I wonder if it’s not a trial to play someone so taciturn, so burdened, for so long? “No. It’s very physically demanding, but I think Jon is quite straightforward. I find I get in a certain mood that maybe can be a bit dour. But I’m nowhere near being a Method actor.”

The son of a businessman and a playwright, Mr Harington grew up in west London, and then, from 11, rural Worcestershire. As boys he and his elder brother, Jack, who now works in fashion, were taken frequently to watch live drama, from prestigious productions to experimental pub theatre. “My brother had to be dragged kicking and screaming to it. I loved it. You go one way or the other.”

The young Mr Harington had two Damascene moments. The first was Waiting for Godot. “That could put you off for life if you saw it done badly. But I was 14 and I was f***ing mesmerised.” Then, in 2004, he saw Mr Ben Whishaw (Q in the James Bond movies) as a famously young and brilliant Hamlet.

“I think he literally was the reason I wanted to act,” says Mr Harington of Mr Whishaw. They’ve since met on two occasions. “I’m not usually bad with meeting actors I admire, but I was tongue-tied both times. I hope I’d be a bit cooler if I met him again.”

Overnight success stories are rarely that – except in Mr Harington’s case he really was plucked from obscurity. He was still at drama school in London, 21 years old, when he was cast as the lead in War Horse, at London’s National Theatre and then in the West End.

“It was unheard of, really, being that young and being the lead on stage at the National. I mean, you work up to that, you earn that. I could never have expected it.”

Next stop: Game of Thrones. Does he ever reflect on the fact that he never suffered the character-building, table-waiting years of struggle most actors are required to endure? “There’s that saying about never find success too early,” he agrees. “And there are moments when I think maybe I would find it easier not to take this for granted if I’d toiled a bit more first. But I’d be stupid to say that I regret it. I’d be stabbed by many unemployed actors, quite rightly. This has opened so many doors to me and it’s my job now to do as much as I can with my career.”

Success is one thing, fame another. International celebrity can do funny things to a man. “It can make you feel like a nutcase some of the time,” says Mr Harington. “It has turned people I know mad. But you just surround yourself with people who don’t kiss your arse, who don’t put up with any kind of arrogance that might be seeping through.”

As for how long his involvement with Game of Thrones will last, he says he doesn’t know for sure and wouldn’t be allowed to tell me if he did. “I can’t speak for how other actors’ contracts work, but I understand the show will run for somewhere between seven and eight seasons.” Meaning a further two or three years, “if I’m in it”.

I ask how he would feel if they killed Jon Snow in the first episode of season six? “I would miss it sorely. I would be very sad to leave. But it would open me up to new things. There’s lots I haven’t been able to do that I would be able to do. So I think I’d be all right with it.”

“Look,” he says, definitively, “I’ve landed a role of a lifetime and it has happened during my twenties and that’s great. Hopefully there’ll be another role of a lifetime down the line but for the moment I can use my thirties, whenever I’m free from this, to go and look for loads of different strange and incredible work.”

That work already includes a sports mockumentary, of all things, called 7 Days in Hell, again for HBO, in which Mr Harington plays an “utterly thick English tennis player” opposite Mr Andy Samberg’s “coke-addled, sex-obsessed, McEnroe-style prick”.

“I had a great time doing it,” he says. “It’s farcical and stupid and ridiculous.”

He’s even more excited about his next project, The Death and Life of John F Donovan, prodigious French-Canadian director Mr Xavier Dolan’s first English-language movie, in which Mr Harington plays a hugely famous young Hollywood actor who becomes embroiled in a tabloid scandal.

“There’s obviously a lot there I can draw on from my own life,” he says. “But actually it’s about finding the differences. [The character] is American, for a start. We’re filming it early next year. It’s a big one, really exciting.”

Before all that, and his (probable) return to Westeros, comes Spooks: The Greater Good, an action thiller based on the popular British TV show. Mr Harington plays a renegade ex-MI5 agent tracking an escaped terrorist.

Like most things in Mr Harington’s life, it sounds like a lot of fun. He must feel very lucky. “It is fun,” he says, “and I do feel lucky… You have to look at your blessings, don’t you? With Thrones, I have to realise that, whatever happens, and for all the stress and the pressure that goes with it, it’s been an extraordinary journey and I know I’ll look back later in my life and think. ‘That was crazy, that was amazing.’ It’s something that very, very few people experience and I love that.”

He says this with great feeling. He’s clearly appropriately conflicted about it all. And for a moment I reflect that perhaps he’s not so unlike the thoughtful, noble Jon Snow after all. Minus the fur collar and broadsword, obviously.

Spooks: The Greater Good is released in UK cinemas on 8 May.