Just before Christmas last year, the String Band‘s Mike Heron could be found playing Cowgate sweatbox Sneaky Pete’s. Healthy capacity 80, 100 max. It was busy, but there were probably tickets on the door. So there’s no begrudging this popular figure in Scottish music his night in the biggest theatre in Scotland, at the country’s most prestigious arts festival. He’s beaming every time he comes on stage and though his voice – never the strongest – is shot to pieces now, he’s very welcome to the spotlight and the adulation he receives. 

This is not the best way to celebrate his music though. The Incredible String Band’s is strange, little music, not well made for such formal settings, and certainly not for the strait-jacket forced on it by this multi-artist tribute, featuring, among others Sam Lee, Barbara Dickson, Green Gartside and Robyn Hitchcock.

Producer Joe Boyd (wearing Mervyn Stutter’s jacket it would appear) unintentionally draws attention to this. He introduces the second half with a winning reminiscence about tripping over cobblestones to discover the nascent String Band playing the Crown Bar – the 1960s avant garde unearthed right here in Edinburgh, as he puts it. But there’s absolutely nothing avant garde here tonight. With this tribute, they have replicated words and notes but none of the spirit. The strongest impression is left by the photo slideshow backdrop of ISB in their prime. In the 60s the sun appears permanently shining, the smiles guileless and hopeful, leafy settings conjure up mythical pasts and technicolour cover art points to impossibly beautiful futures. It’s enough to make you weep. 

Then cut back to 21st century reality. The stage is a mess of mics and music stands. Mics are not turned up. Guitar leads buzz. People forget to introduce each other. There’s cross stage glances as people wonder if they’re supposed to be singing. Though individual parts have been worked through, the collective appear to have had very little rehearsal time together.

And the music, while perfectly pleasant, feels empty. Withered Hand extracts all the weirdness out of The Hedgehog’s Song, with Karine Polwart and Dickson providing ineffectual backing. Green Gartside’s First Girl I Loved is better, and he talks very sincerely about how much the band mean to him (he was knocked down by a bus running excitedly from their 1971 gig). But both he and Hitchcock seem uncertain whether to copy the original meandering intonations or stick to their regular singing voices.

The provision of new musical settings certainly has the potential to re-invigorate pieces, but why choose opera? Janis Kelly takes a couple of songs without any explanation of what the music means to her or what the operafication is meant to achieve. A grime re-working would have been laughably terrible but would at least have been an attempt to replicate the  freshness of the sound. Too much of this concert leans on the conservative folk instinct to preserve and not the radical folk instinct to evolve, the instinct that forged that golden period of the 60s/early 70s. 

That said, unquestionably the loveliest moment is Karine Polwart’s October Song, tenderly rendered in a traditional style. “Karine Polwart sings the Incredible String Band” would be a wonderful concert, but not here, and not as a definitive tribute by the nation’s cultural aristocracy.

The recent BBC Scott Walker prom was a fabulous example of how to pay respect to great artists. But as Scott Walker is suited to the grandness of orchestras and the Royal Albert Hall, so ISB is suited to an earthier setting. It needs candles and trees and a sense of adventure, not music stands and opera.