Rob Adams

If anyone misses a cue during Celtic Connections 2015's opening concert at Glasgow Royal Concert Hall tomorrow [Thursday], Greg Lawson will surely be able to step into the breach. The man who has taken on the challenge of scoring the late Martyn Bennett's final masterpiece, Grit, has developed an enormous repertoire of doofts, paaarps, whaaaps and squeaks to explain the sound he's after.

The musicians - indeed, everyone - involved should also be warned that Lawson has their speech mannerisms down to a fine art. The trombonist making that funny noise with a mute; the late Skye bard Calum 'Ruadh' Nicholson, whose contribution to Bennett's track Why will be the concert's only sampled sound; Bennett himself - they all appear with uncanny realism in conversation with Lawson.

Lawson, who was friends with Bennett and apparently told him that he was going to get musicians to play the work that Bennett created electronically (cue a scarily perfect Bennettian "Are you now?" in staged response), has been talking about performing Grit live since Bennett died in 2005. With some kindly bullying from Celtic Connections' artistic director, Donald Shaw, he finally sat down in the middle of 2014 to finish what he'd started some years before so that the performance could mark the tenth anniversary of Bennett's passing. It's been six months of having Grit on 'play' in his head, he says, adding that his sleep patterns have gone so awry that he's written a tune called 4am that he now plays with the klezmer-jazz band Moishe's Bagel.

"Donald has been brilliant," says Lawson. "Every conversation we've had has been geared towards making this happen. Even when I've gone to him and said, 'We need eight monks to sing the Gregorian chant on Blackbird,' he's said, 'No problem, we'll get you eight monks.' We don't need monks, just singers. But the knowledge that whatever obstacle we face, we can deal with it has been a great incentive to get this music to the point where it's all written and printed and ready to play."

It's partly because Grit has become an iconic album following Bennett's tragically early death at the age of thirty-three that Lawson feels so strongly that it has to be performed.

"Grit's a fabulous piece of work," he says. "But it tends to live only on people's stereos or on their headphones or in their cars, and to me that's not enough. That makes it like a monument you can visit when it should be breathing. Yes, it was all made with machines but Martyn put such heart and soul and dedication into creating this music that the album sounds like a living thing. I thought, well, it's a massive landscape of sound, why don't we bring in the instrument that's been developed over centuries now to transmit massive landscapes - the orchestra - and in a way, reclaim this music for the concert repertoire?"

That music is meant to be played has always been Lawson's philosophy. Whether it's been Beethoven symphonies, traditional reels, heavy metal or prog rock, he's found a way of translating what he's heard onto his violin. He hasn't always enjoyed wearing a suit and tie to play in orchestras including the Scottish Ensemble ("Me granny always told me that when I wore a suit, it looked like I'd stolen it," he adds in said grandmother's Geordie brogue) but Grit, he says, has made him listen to orchestral music differently.

"My ears have got bigger," he says. "Not physically, I hope, but I've found myself sitting in the BBC SSO violin section and thinking, that's a nice texture, how did the composer achieve that?"

Finding out how Bennett achieved some of the sounds on Grit only increased Lawson's admiration for a musician who could spend two weeks perfecting the tone of one electronic drum beat.

"The great luxury I've had is that I've been able to bring in musicians I know from the classical, folk and jazz worlds who will all add their individual skills," he says. "They're getting instructions they'll never have had before but they're all up for making it work."

Some musicians have dropped out. One got the opportunity of a holiday of a lifetime and Lawson told him to grasp it. Another learned that the BBC were filming the concert and refused to perform due to the corporation's coverage of the Referendum. And another, singer Sheila Stewart, passed away last month, depriving Lawson of one of Grit's great character-voices.

"The wonderful thing about Martyn was that he knew people like Sheila and he loved their characters and valued their place in the folk tradition," he says. "When he sampled Sheila singing the Moving On Song she became an integral part of this very human, machine-made music and now this vast landscape that one man put together with painstaking patience and imagination is going to be performed by a cast, not quite of thousands, but there's a heckuva lot of them."

"Nae Regrets" launches Celtic Connections 2015 tomorrow evening at Glasgow Royal Concert Hall