NTS artistic director Vicky Featherstone is in optimistic mood on its fifth anniversay

26 CIVIC STREET, GLASGOW, is not a glamorous address. The building is a piece of workaday Victorian architecture, like the office or counting-house of a long-vanished mill; the location is a windblown patch of industrial park just north of the M8, at the old Port Dundas basin of the Forth and Clyde Canal.

Yet for all its unassuming appearance, Civic House – as it aptly calls itself – is the headquarters of the National Theatre of Scotland, and inside its front door, the little building buzzes with activity, from the row of modest offices on the first floor to the small rehearsal room near the front entrance, where a company of five actors and musicians are rehearsing the NTS's current touring pub show, The Strange Undoing Of Prudencia Hart.

The show is a postmodern remix of the Border Ballads tradition, written by leading Scottish playwright David Greig, with music that ranges from traditional reels to the songs of Kylie Minogue. From time to time, exuberant waves of sound make their way up to Vicky Featherstone's little first-floor office – a room with a view across the motorway, towards Cowcaddens underground station – as she looks back over the first fierce half-decade of the organisation she leads. Founded on a completely new model for a national theatre institution – one devised by the Scottish theatre community itself, in the late 1990s – the NTS is famously a "theatre without walls", neither a building not an acting company, but a body charged with using its 4.5 million a year of public money, direct from the Scottish Government, to enrich Scotland's theatre culture by working with and through existing companies and groups of artists. True to its brief, the company launched its work, exactly five years ago this weekend, with ten experimental site-specific shows on the theme of "Home", staged simultaneously in non-theatre locations all across Scotland, from a Drill Hall in Dumfries to the car deck of the Northlink Ferry, docked in Lerwick harbour. Since then, the NTS has staged no fewer than 137 shows, ranging from high-profile Edinburgh Festival productions like last year's much-criticised Darien drama, Caledonia, to year-long youth and community projects in areas across the country.

There is no doubt, though, that the ride has often been a bumpy one, marked by controversy about the company's repertoire – edgy, postmodern, and addicted to the new – and by questions over its success in fulfilling one of its major remits, which is to provide world-class large-scale drama for Scotland's big touring stages. Of the 137 shows, just two – the legendary Black Watch, launched during the Edinburgh Festival of 2006, and Dominic Hill's fabulous Dundee Rep co-production of the almost unstageable Ibsen masterpiece Peer Gynt, in 2007 – have been unambiguous large-scale successes.

For the rest, there has been a gorgeous cacophony of site-specific experiment, exciting new work, and innovative projects with young people in specific communities, producing occasional small-scale gems, like the wonderful 2007 touring adaptation of Luke Sutherland's complex Orkney novel, Venus As A Boy; and certainly no-one could fault the NTS's massive effort to reach out beyond the Central Belt, and to form special bonds with communities from Orkney to Fife.

On the main stages, though, the company has struggled to exorcise the ghost of Black Watch, a study of Scottish squaddies in the Iraq War so magnificently staged by Featherstone's new work director John Tiffany that it emerged as one of those rare once-in-a-generation theatre events with the power to attract whole new audiences to the art-form.

The other large-scale shows, though – like Caledonia last summer, or David Greig's dark version of Peter Pan, launched last spring – have often been dogged by a nagging combination of sheer bad luck and slight misjudgment, as if the very scale of the resources available had slightly dulled the artistic decision-making. And those who look to the National Theatre to provide a more conventional diet of Scottish stage classics – led by the veteran campaigner Paul Henderson Scott – have been disgruntled by the company's refusal, so far, to start ploughing its way through the back-catalogue of established Scottish drama; disgruntled, in a few cases, to the point of making shameful jibes about the fact that neither Featherstone nor Tiffany was born in Scotland, although both have demonstrably shown far more commitment to living and working here than many native Scots in showbusiness.

Despite the brickbats that come with the job, though, Vicky Featherstone seems remarkably upbeat, as she surveys the world from her tiny office sofa. "Of course, you do take a lot of criticism in this kind of job," she says. "And yes, there could be a tendency to develop a kind of bunker mentality, where you just stop listening. But our response, I suppose, is always to resist that by trying to shift to the opposite extreme, to open up the debate rather than closing it down, and to try to include as many people as possible.

"So this year, for the fifth anniversary, we're trying to do three things, which I think will strengthen our relationships both with audiences and with artists. One thing that strikes me, for example, is that the model we operate is so complex, and so flexible – in that we like to be responsive to ideas that come in, and not to have the same pattern of work each year – that people often find it difficult to see the whole picture of what we do. So this year, for the first time since 2006, we've announced the whole year's work at once, so that people can see the whole range of what we'll be doing, across 2011.

"Then, secondly, we want to keep on building new relationships with theatre artists and companies in Scotland, as well as developing existing ones. It's in the nature of the model we operate that we have to turn down more potential collaborations than we can ever take on, and that's bound to cause a certain seething resentment in the theatre community.

"The advantage, though, is that I'm clearly an artistic director, not an arts council bureaucrat. I feel a tremendous responsibility for the public money we get, but it's an artist's responsibility, to the places in Scotland where we work, and to the stories that need to be told. So I'm happy to make those choices on an artistic basis, and to defend them on that basis, and I know within myself that I'm not making malicious decisions, so I can live with the criticism.

"And then finally, for this year, I want to do something about leaving a legacy for the future, in terms of leading the debate about Scottish theatre, and raising its profile as part of our national life. We've listened to what's been said about our repertoire, and one of the things that's become clear to me, as I've been doing this job, is that Scotland is full of conflicting ideas about what our theatre tradition is. Say what you like about English theatre – and it has plenty of downsides – there's not much dispute about what the basic elements of the tradition are; about the position, say, of Shakespeare, or Oscar Wilde. Whereas in Scotland, the story is much more fragmented and contested.

"And increasingly, we want to be a platform for discussion about that. It's partly reflected in our programme of productions for this year – one of the reasons we're doing Ena Lamont Stewart's Men Should Weep later in the year, and David Harrower's Knives In Hens, is that we're asking, 'What is a Scottish classic?' And in addition to that, we'll be running a whole series of debates and events, throughout the year, that will looks at the history of Scottish theatre, the strands of work within it, and the canon of plays that has emerged. I'm hoping Alan Cumming may be able to curate an event on the variety tradition, for example. Because I do feel that I am just the guardian of all this for one moment in time; and one of our roles should be to support that debate, so that the whole thing can become sustainable in its own terms, and be handed on into the future."

There's no sign, though, that Featherstone – who is bringing up her two children in Glasgow, with her scriptwriter husband Danny Brown – wants to make that handover any time soon. In fact she shouts with laughter at the question.

"No, in many ways I feel I'm only just realising how to do this, it's just a complex job! And the model has its challenges, but in the end I think it is a genius model that the Scottish theatre community came up with. It absolutely forces us to be at the forefront of theatre, thinking all the time about why we want to do what we do; and I would defend it to the death. So I love the job more than I ever did, and I don't have any view about leaving at the moment.

"We've got a packed programme coming up, including two plays I'm directing myself, that I can't wait to get started on. And I've got so many ideas about discussions we could stage, from a session about Glasgow School of Art and its impact on Scottish theatre, to a debate – say – between David Greig and Paul Scott about the language we use in theatre. There's so much to talk about, so much to do. And to me, it all feels as if it's just beginning."

Click next for more on this year's highlights...Five past highlights...

1 FEBRUARY 2006: NTS signals its radical intentions by launching not with a glittering premiere in a big-city theatre, but with "Home", a series of ten simultaneous site-specific shows staged in non-theatre venues across Scotland, from Dumfries and East Lothian to Stornoway and Shetland.

2 AUGUST 2006: audiences, including Sir Sean Connery, emerge shaken, stirred and thrilled from the Edinburgh Fringe premiere of the mighty Black Watch, the NTS's multiple award-winning global hit about Scottish squaddies in Iraq. Black Watch tours across three continents, and is still on the road today, with upcoming dates in Glenrothes, Warwick, and Chicago.

3 SEPTEMBER 2007: in Tay Street, Dundee, the arrival of a pink party limo full of shrieking, karaoke-singing wedding guests signals the start of Dominic Hill's masterly postmodern production of Ibsen's Peer Gynt, which goes on to thrill audiences in Edinburgh, Glasgow and London.

4 JUNE 2009: In the bright Orkney midsummer, the NTS presents its outstanding young people's project Mixter Maxter, created for and with younger secondary schoolchildren, and exploring the dynamics of teenage island life, with its recurring dreams of escape. The show is great; the installation, at an old ropeworks near the waterfront, is unforgettable.

5 FEBRUARY 2010: At the SECC in Glasgow, Vicky Featherstone enrages her critics, and boldly prods the boundaries of theatre, by starting the year's programme with a show called Wall of Death, featuring the Fox Family troupe of wall-of-death bike-riders. Was it theatre? No-one could agree; but it certainly kicked up a rare dust of debate.

What to watch out for in 2011

1 MEN SHOULD WEEP: the NTS finally commits to a production of Ena Lamont Stewart's great 1940's classic of tenement life, recently staged to great acclaim at the National Theatre in London. Opens at the Citizens' Theatre, Glasgow, September 2011

2 DUNSINANE: in a first-ever co-production with the Royal Shakespere Company, the NTS presents the Scottish premiere of David Greig's recent variation on the Macbeth story, in which the queen, Gruoch, played by Siobhan Redmond, survives the carnage, and goes on to play havoc with the English army of occupation. Opens at the Royal Lyceum, Edinburgh, May 2011.

3 STAGING THE NATION (1): a year of debate on the history and tradition of Scottish theatre kicks off at the Traverse Theatre on 15 March, as playwright Chris Hannan chairs a session in which John Byrne and director David Hayman debate Byrne's great Slab Boys trilogy of the early 1980s, and its lasting impact on Scottish theatre.

4 FIVE MINUTE THEATRE: on Midsummer's Day, for 24 hours non-stop, the NTS presents a live online staging of five-minute plays written by anyone in Scotland, in any style, about anything. To pitch your idea, or just find out more, go to www.fiveminutetheatre.com.

5 THE MISSING: John Tiffany directs a new stage version of Andrew O'Hagan's wonderful 1995 book about the texture of Scottish small-town life in the 1960s and 70s, and those who slipped through the gaps in the social fabric. Opens at the Tramway, Glasgow, September 2011.