Video: John Tiffany on quitting Scotland and confounding the critics

Maybe he already has, in a way. For the past two years he has been globe-trotting more and more. He made his Broadway directorial debut in 2011 with the musical Once (he picked up a Tony award for that) and since December 7 – the night of his and NTS artistic director Vicky Featherstone's leaving do – he's been in New York, Boston, London and Dublin (directing The Glass Menagerie and overseeing Once's debut in the West End) and Glasgow hardly at all.

So it's tempting this fine Govan morning to see the next few weeks as a kind of farewell. "Yes and no," he says, as we sip tea in the cafe at Film City, two incomers (him from Yorkshire, me from Northern Ireland) who came to Scotland and stayed, in his case until now. Tiffany is here rehearsing Let The Right One In, which opens in Dundee next month. He's in his shorts and T-shirt because he's been warming up with the cast. There are spots of white plastic – the substance that's standing in for snow in this theatrical take on the Swedish vampire film – clinging to his neck and clothes. "Black Watch is still on," he continues. "Macbeth is going to be running and there's another project in a few years time that I would love to do."

Watch the trailer for Let The Right One In below.

Video from National Theatre of Scotland on Vimeo

Even so, he's leaving to become associate director at London's Royal Court Theatre, where he'll team up with Featherstone again. His home, in Kelvinbridge, is up for sale and he's been taking his friends and colleagues on trips round Scotland. "I feel a bit like Cher on a farewell tour," he admits, laughing. "I'll always come back and have a relationship, but I'm moving to London in the summer and I'm looking forward to it. Evolve or die."

It will be a big shift. He came as a student to Glasgow in 1990, the city's Year of Culture. He soon shifted from studying biology to theatre and classics, worked at the Traverse in Edinburgh and with Paines Plough before joining up with NTS and helping create some of the most formative and – yes, let's say it – important theatre of the past decade.

Tiffany's approach to theatre is, he says, visceral rather than intellectual. He's done war stories and love stories. Black Watch – about Scottish soldiers in Iraq – is his best-known work, but it's only one of a number of highly regarded NTS shows. He's pleased people are looking at it as a body of work. "Sometimes not within Scotland, but certainly outside Scotland." He pauses slightly. We're only a few minutes into our conversation and there is something unsaid hanging in the air. "We've both been here," he says, obliquely.

We're both colonists, I joke, referring to Alasdair Gray's controversial comments, reported by the Sunday Herald, that the English were taking over the arts in Scotland. "The 'c' word," he says. "I prefer the other one." He pauses again, sips his drink and then plunges in.

"I'm not going to trash my exit but it is refreshing not to be on salary and have the responsibility of toeing the party line when things like that happen. Because that's not the Scotland I know and love. Stop going on panels and accusing people who are making life choices to do with their families. They're not from Scotland, but particularly in Vicky's case this is only cause for celebration.

"How dare you. How dare you! Really. That's somebody who's decided to move her family and her kids and has taken an opportunity and is leaving a really robust company is cause for celebration. Write a book or a play. Stop tittle-tattle.

"You can tell it exercises me, because I find it sad. It's better than that, Scotland."

There are two things to note. The first is Tiffany's vehemence. The second is that really it's not himself he's defending, but his friend Featherstone. "She'll be criticised for her work and her taste now, not for the fact she's English, which you can't respond to. It's a fact. It's that that is inherently bad that I find amazing people can get away with. Our two national papers – yours included – printing letters which perpetuate that. I'm from Yorkshire which is quite a similar culture and feels as badly done to by the south. I understand the beef. I get it."

Tiffany clearly sets great store by his friendships. He works again and again with people he knows and loves, such as Featherstone and Steven Hoggett, who's also working on Let The Right One In and whom he's known since he was 15. Friends matter.

Much has been made in the past of his childhood on the edge of Saddleworth Moor, a very happy childhood of brass bands and amateur drama (though he also recalls voraciously devouring stories about the Yorkshire Ripper and seeing the police helicopter bringing Myra Hindley back and forth to the moor where the bodies of her and Ian Brady's victims were buried).

Maybe the key to Tiffany's story, though, is the decision, at 15, to go to sixth-form college in Huddersfield. That's where he met Hoggett and friends who have remained friends ever since. "That's when I felt at home," he says. "We were pretentious. We went to Manchester to buy our clothes and we started going to the Hacienda and suddenly that whole world opened up to us. We thought we were it, but also we were different. I feel at home slightly outside and I'm with people who make me feel great, who stimulate me, who I can make sexual experimentations with. Anything's possible. And then I came to Glasgow."

The idea was to be a doctor. But maybe that was just to placate his parents. His mother had been a nurse. "I don't know if I thought I was going to, ultimately. I was going through the motions." How did his parents react when he switched courses? "My mum and dad were supportive. I think they were just scared. But also from my mum's point of view, if you could be a doctor why on earth wouldn't you be?"

The reason is what he found here. Being exposed to the likes of Robert Lepage's immersive theatrical experience Tectonic Plates during the Year of Culture changed his direction. "I was out for dinner with Graham McLaren, the associate director of NTS last night, and we were saying we wouldn't actually be the people we are or certainly the people doing these jobs if it hadn't been for 1990."

Glasgow offered something else too. Something different. He met new friends and felt very at home in what he calls Scotland's "demotic society". Even the theatre was different here, he says. "I loved the fact that Scottish culture was a mish-mash of art forms. I think that absolutely moulded me."

He met Featherstone in 1993, while doing a work placement at the West Yorkshire Playhouse where she was running a street theatre festival. "She had a peroxide skinhead and she was telling me about the festival and I was like: 'Wow.' I can't remember this but apparently we left lunch and five minutes later there was a knock on her door and it was me saying: 'Look, this is my last day, but I think you're really inspiring and I'd like to work for you for free all summer.' She actually gave me a job and paid me. She was living in Manchester but working in Leeds and that was a real summer of madness."

He won't go into details but he does tell me about dancing with Bjork. "One of Vicky's best friends ran a record promotion company who promoted Bjork when Debut came out and we went to see her at the Manchester Academy. We went out clubbing with her. We were dancing away to this mad dance music and she whispered: 'I have a polar bear in my living room in Reykjavik.' And I was like: 'A live one?'

"I came back from that summer and announced to all my friends I'm a director now. I wanted to be Vicky because she was directing. So I started directing."

How easy is it to get up on a stage and say you're in charge? "Well, 50% of directing is saying: 'I'm a director.' People go: 'OK.' Then you start to learn how to do it and it's very painful and humiliating, but you keep going. It's a craft."

Clearly he loves theatre, but it's a tough love. It's too middle class, for a start. "I agree that a lot of theatre is made and fuelled for that, and I try to challenge it. It angers me, it gives me bite and it gives me a mission. I think a lot of what we do is rubbish -"

Rubbish? "Not good enough and we're complacent. And it's that thing of the word 'should'. When people say: 'Oh, I should go to the theatre.' We've got to get rid of that. That there's some kind of inherently healing goodness about going to the theatre, like going to church. Because that will be the death of us. People don't say: 'I should play video games.' They don't say: 'I should go to the pub more.' They're things that they enjoy. We have to make theatre that people can't not go to. I think a lot of what we choose to put on stages and the way that we do it and the fear that the audience have of letting new audiences come in is bulls***."

Perhaps I'm making Tiffany sound too serious. He is, but he's chatty and funny and self-deprecating too. He'll tell you about his terrible first attempt at making a short film. He'll tell you about the nights that end in sing-songs at his home. "The only time the police have been called to my house is at parties when I sing."

But he's serious about what he does and its place in the world. Black Watch, perhaps more than any other show, changed everything for him. "Absolutely," he says. "Black Watch is the one. When I sit in Stephen Sondheim's living room drinking wine with him and talking about a show that we might do together, it's because he went to Black Watch and took a coach party from Manhattan because the friends he was taking didn't know where Brooklyn was.

"When I get letters from young directors it's [because of] Black Watch and that's amazing. And when I'm in Glenrothes and the mother of a dead soldier says 'you've given my son back to me for two hours' that's -" For once he runs out of words.

Once did win him a Tony award, of course. "It was a great night. I'm a Hacienda boy – we're up for a good night. It gives me a bit of freedom because the Tonys are a massive thing. It buys you a certain security, though I realise you need very little money to live. I'm realising if you're doing what you love and you don't live in massive houses and you don't have kids you need very little money. I still bring in a packed lunch at times."

Once is a love story. When did Tiffany first fall in love, I wonder. "When I was 15." Was it requited? "Yeah - yeah - I haven't fallen in love that much but all the people - bar one - I've fallen in love with are still in my life.

"I think when you fall in love you never really fall out of love, ever. It becomes corrosive in terms of the way you treat people but you never fall out of love because there's always a memory there. So I think that's really nice, apart from one person who we'll call the 'c' word – not colonist. I've still got the capacity to fall in love."

Are you in love now? "Semi, yeah. Oh God, that will get me in trouble. No, actually, it won't get me in trouble. I've been a serial monogamist for 15, 16 years up until 18 months ago and now because I'm in London, Boston, New York, Scotland, I'm really enjoying that. I like that American thing of you can date a few people at once."

Is there a John Tiffany coming-out story? "Not really. Again, meeting that group of people when I went to sixth-form college, knowing that some of them were gay and then coming to university and entering theatre where it's practically illegal not to be. But I've never been part of an only gay world, so Glasgow for me was the Sub Club and the Art School. That's where I found my real home and my first brilliant boyfriends."

John Tiffany is 41. He's achieved so much more than he'd ever dreamt of wanting to achieve. "I sometimes say this as a joke but if it went tits up I would be happy making cakes in Penrith with a cake and book shop – my two favourite things are making cakes and reading books. As soon as you achieve something you didn't know you wanted to achieve ambitions went out the window. My ambitions are for the work, not for me."

Before he retires to Penrith he might make a movie (but only one), and no doubt there will be more memorable theatre to be made at the Royal Court, his new home. Right now, though, he has a show to rehearse. And so I leave him where he's happiest. This is an ending. But all endings are beginnings too. n

Let The Right One In opens at Dundee Rep Theatre on June 5 and runs until June 29. For tickets, visit nationaltheatrescotland.com.