Debuted at Celtic Connections in 2015, it felt not only appropriate but somehow essential that this project migrate at some point to Edinburgh in August; that it ended up arriving at one of the Edinburgh International Festival's grandest venues in the first ever collaboration between EIF and Celtic Connections was no overplaying of the scale of the thing. Arranged and conducted by Greg Lawson, this orchestral reinterpretation of Grit – the final album by the late Canadian-born Scots folk composer Martyn Bennett, who died at the age of 33 in 2005 from Hodgkin's lymphoma – was a staggering, celebratory affair, one packed out by an inter-generational contingent representing generations of Scotland's folk scene.

In fact, that description could have been levelled at the stage alone. Lawson, smart-suited and warmly impudent, stood atop a small podium, conducting what looked from the stalls like at least thirty string players, whose playing in unison recreated the fierce electronic power of Grit. It's a singular record, one which fuses not just the folk traditions of Celtic music through rich, emotive pipe and fiddle lines, but also takes on board a kind of cut-up, free party techno spirit and the driest of Scots senses of humour. The classical element which permeates the record was accentuated much further here; it was the most appropriate expression of what the Edinburgh International Festival should be hosting in the 21st century, a fusion of traditional styles and new musical forms which are all resolutely Scottish.

The massed strings were joined by a smaller brass section; a rhythm section; a six-strong chorus of singers featuring Karen Matheson, Rab Noakes, Fiona Hunter, Innes Watson, Mischa MacPherson and Sorren Maclean; the University of Glasgow Chapel Choir; and a bagpipe player who became possibly the musical focal point of the evening thanks to the blasting riff which formed the centrepiece to the wild, techno-timed 'Chanter'. In the background, the actor David Hayman intoned the biblical spoken lyrics of 'Liberation' (a role originally taken by Michael Marra) with grave intent.

It transformed the original, but in a manner which was nothing but respectful, and clearly outwith the budget which Bennett may have had to realise his music. A sobering moment came towards the end, when Lawson pointed out that Bennett's family still bear the debts he accrued recording his music, and that any CD sales would be very much appreciated. Such earthly concerns seemed to pale next to Matheson's voice soaring through the swooning ambience of 'Blackbird', or the gleeful encore of 'Chanter', or Lawson conducting the audience in a glorious chorus of the 'Paisley Spin' lyrics 'to each and every one of you, I say goodbye, farewell, adieu …' while the orchestra poignantly vacated the stage.

Seen at the Playhouse, Edinburgh, Tue 23 Aug, run ended.