Reaping the harvest of Scottish theatre

Every year, the Edinburgh Festival rolls on, looking much the same, a mixture of the surprising, the predictable, the dreadful, and the sublime. And every year it throws up a new debate. You know the type of thing: "Has physical theatre killed play-writing?"; or that hardy perennial: "Why are the Irish so good?" This year's talking-points might be 11 September, or perhaps pornography, but early indications suggest that it is, intriguingly for me, shaping up to be: "The Surprising Strength of Scottish Play-writing".

Rona Munro, Anthony Nielson and I have plays doing well at the Traverse. David Harrower's translation of Girl on a Sofa, and Douglas Maxwell's Variety are centrepieces of the international festival programme.

On top of this, Gregory Burke's Gagarin Way, the hit of last year's festival, continues its relentless cruise towards world domination. When The Guardian recently published a list of 10 playwrights who will be "the future of British theatre", four of them were Scottish or Scottish-based writers. To the outside eye, this must all seem rather sudden, and it would be an easy leap to suggest that it represents the blossoming cultural confidence of a newly devolved nation. But, inevitably, that would also be wrong.

Scottish play-writing is very strong at the moment, but the truth is, it has been strong for a quarter of a century. The new generation of Scottish writers didn't come out of nowhere. The roots of the current success lie primarily in the Eighties, and in the incredible, groundbreaking and beautiful play-writing of Chris Hannan, Liz Lochhead, Ian Heggie, John Clifford, Simon Donald and John Byrne. These playwrights, writing in the immediate aftermath of a failed devolutionary referendum in 1979, and in an atmosphere of distinct cultural cringe, forged a new, confident, bold language of theatre in Scotland. A new theatre that was, I believe, in part responsible for devolution eventually arriving.

Scotland is a small nation of five million people. Six hundred thousand of those people, according to the Arts Council "regularly go to the theatre".

The effect of those plays – Mary Queen of Scots Got Her Head Chopped Off, Elizabeth Gordon Quinn, Life of Stuff, The Slab Boys Trilogy, and many others – was to build a new image of Scotland into the cultural debate and into the minds of half a million or so Scots. These writers were relentless truth-tellers, refusing to perpetuate our own comfy stereotypes. They used an extraordinary variety of demotic language to forge a poetry that dislodged standard English from centre-stage, but that also questioned and rejected "standard Scots" or "the Lallans", which would have consigned Scottish theatre to an outpost of folkloric pastiche. Politically, they reinvented opposition, avoiding agitprop in favour of a more tangential, globally aware, self- deprecating and comic political voice to counter the rabid discourse of Thatcherism.

I know that in my own case, I wouldn't have begun writing plays had it not been for exposure to these writers. But I also know that, in a canonical sense, they created a tradition of Scottish play-writing that continues to bear fruit. If there is a link between the work of the new Scottish writers, then it lies in this tradition.

So, what does the tradition consist of? What defines the new Scottish play-writing? All of them are unafraid of structural experiment and collaborative work. Douglas Maxwell wrote Decky Does a Bronco, to be performed in playgrounds and works, extensively with Grid Iron – an experimental company based in Edinburgh. Isobel Wright and Nicola McCartney have both worked successfully with Frantic Assembly. My own work with the collaborative company Suspect Culture, Rona Munro's work with MsFits, and Anthony Neilson's with his company, the Red Room, seem also to point to a lack of fear among Scottish writers of creating your own structures in which to work, treating writing as a part of the whole experience of theatre – not its only component. That is an attitude that is bound to foster structural play and formal daring.

The other key link, for me, is poetic. Every one of the writers I've mentioned has a very distinct voice. Their plays carry the sense of language handled with the poet's care. Zinnie Harris's incredible linguistic invention in Further Than The Furthest Thing would be an example, but so, too, would David Harrower's work in general and, in particular, his translations of Woyzeck and Ivanov (soon to be on at the National Theatre).

Of course, many English playwrights are structurally daring, and many have poetic voices, but most of them – Sarah Kane, Howard Barker, Martin Crimp, and, to some extent, even Caryl Churchill – have tended to be regarded as marginal. In Scottish theatre, the mainstream is, and has been for some time, poetic and experimental. Whether that be Liz Lochhead's incredible reinvention of Scots in her Molière translations, which sold out the Lyceum, or Chris Hannan's beautiful play Shining Souls, whose success in Scotland was never matched in London.

Scottish theatre has traditionally not done well in London. Not in comparison, say, to the reception of Irish work. When plays have done well, Trainspotting and Gagarin Way, for example, they tend to be plays of underclass violence and comedy. This doesn't diminish those plays, but it does suggest to me that the London critics feel most comfortable with Scottish work when it fits their understanding of Scots – violent and funny poor people who are slightly frightening. The softer voices, the poetic voices, and the experimental voices are met with bemusement, apathy or patronising disdain.

The wellspring of the Scottish tradition of experiment is found in the work of an Englishman, John McGrath. In a sense, McGrath is the single individual most responsible for shaping the bones around which Scottish play-writing has grown. Political, experimental and poetic – it's all there in The Cheviot, the Stag and the Black, Black Oil. His last play, Hyperlynx, is staged on the Fringe this year. I wonder how many of the theatrical establishment who are asking this year's question will make their way to the Pleas-ance Dome to see McGrath's play and to write him back into this year's story.

David Greig's play 'Outlying Islands' is in rep at the Traverse theatre to 24 August (0131-228 1404)