In a room off Aberdeen Art Gallery's Sculpture Court café, just a few yards from where a dozen or so mostly elderly patrons are sipping coffee and nibbling pastries, Billy Letford, 36, is limbering up for a flash-mob "happening".

It is not true to say the sippers and nibblers are unaware there is something more than espressos brewing this morning - Letford may be off stage, but a couple of musicians are tuning up in one corner, a photographer is lurking in another and a man is sitting hunched over a laptop nearby. He is wearing headphones and pointedly not sipping or nibbling or looking at paintings.

But if the interlopers lack the element of surprise that most flash-mob events rely on, they will make up for it by the vigour and invention of their sonic attack. Much of that will come courtesy of Letford, a fast-rising performance poet from Stirling whose now well-mined story - until recently he worked as a roofer in the family firm and was in the habit of leaving poems inked on joists in attic spaces - shouldn't detract from his literary gifts.

More of him in a minute, but first the man at the laptop. He is Irish composer Brian Irvine and the musicians are members of the Red Note Ensemble, one of Scotland's leading contemporary music groups. Among them, on cello, is Red Note co-director Robert Irvine (no relation). Also present are a flautist and, wandering around upstairs somewhere looking for the acoustic sweet-spots, a trumpet player.

In collaboration with Brian Irvine, the Ensemble has created a piece called Framed Against The Sky. Centred on Letford's specially composed verse, it will incorporate elements of this "happening" and others like it which have taken place around Aberdeen over the past few months. The work will have its world premiere in Banchory on October 23 when it opens Sound, the north-east's adventurous festival of new music. Among the other enticements on offer are performances by genre-defying electro-folk singer Leafcutter John; film screenings accompanied by electronic music; and numerous collaborations between visual artists, classical ensembles, filmmakers, dancers and scientists. The nights may be drawing in, but over the next month Aberdeen's artistic boundaries are heading in the opposite direction, reaching out to musicians from as far away as Syria.

Now back to Stirling boy Billy Letford who, after a roaming performance of poetry backed by the improvising musicians, has taken a seat opposite me in the café. "The piece I've written is a journey, from space through to a workman on a roof and then into someone's garden. So it comes from a huge, massive space to one single point at the end," he explains. "Part of it is to do with the experiences I've had as we've been going around, and some of the words I've written will be sung by people that we've met in the workshops."

In that sense, today's event is also a recruiting drive as well as an attempt to take new performances into the community. In between verses, Letford has been sweet-talking the café punters to see who might be willing to participate in the eventual performance. To that end, he and the musicians have also visited a life drawing class, a hillwalkers' visitor centre, primary schools and tourist attractions such as waterfalls and a cave. When they finish here, they will lug their music stands and cello cases down the road to another café and do the same thing again. Footage and recordings from these and other events will form an audio-visual record of the project.

On the table beside Letford is the notebook in which he writes the verse he "tells". "I say telling because I'm not reading," he answers when I question his use of the word. "I write it on the page, it's published on the page and it works on the page. But I choose not to read it from the page." Partly it is that ability to maintain eye contact with his audience, as well as his unforced charisma as a performer, which have put Letford on Scotland's literary map over the last half-decade. But a Scottish Book Trust New Writers award in 2008, a subsequent publishing deal with Carcanet Press, a 2012 collection and an MLitt in creative writing from the University of Glasgow have all helped too. As has the vibrancy of the work itself, of course.

Letford began writing verse at primary school, though not unbidden: given the task of writing a poem as homework, he woke up one morning, remembered that he'd forgotten to do it, turned on the television and saw news coverage of the 1987 King's Cross fire. He wrote a poem about a father and son caught up in the disaster and his teacher liked it so much she sent it to Roger McGough. The Mersey poet wrote back with the avuncular admonition: "KEEP WRITING!" Letford still has the letter, though the poem itself is long lost.

"So I had this thing in my mind that I could write poetry," he says. "But at high school I didn't do it at all. Then when I was 23 I lost my job and I thought, 'What do I actually want to do? I want to be a writer.' And when I started to write, it just came out as poetry."

For the next few years he bent his friends' ears at parties with his versifying. He worked as a roofer in the family firm and, inspired by that bird's eye view of the world, scrawled verses on the hidden parts of the homes he was building. He attended a writers' group in Stirling and applied for creative writing modules wherever he saw them advertised. It was through one of these that he first performed his work. "I memorised the whole thing and I just got up and did it. For me, getting up like that feels natural."

All the time he was writing, he was also reading. "I was stumbling across things. I went to a reading by Tom Leonord and I was really struck by it. That opened up the whole Scottish canon - Jim Kelman, Liz Lochhead - and I started to read those people and I started to recognise my voice. Before then I was reading stuff like TS Eliot that wasn't my voice. It wasn't speaking to me. Now, I know that he's great - but then I couldn't access it. I had to come back down and come in through a different voice."

In 2008, he was encouraged to apply for both a Scottish Book Trust New Writers award and, though he didn't have a degree, a place on Glasgow University's creative writing course. In 2011, Carcanet Press included his work in its New Poetries V anthology and a year later, under the name William Letford, published his first collection, Bevel.

Last month, meanwhile, he featured in Canongate's Future 40 list, a compilation of two-score storytellers whose voices (or so the publisher thinks) will dominate the next four decades of Scottish life. Letford and Michael Pederson are the only out-and-out poets on a list which also includes Scottish Album of the Year winner RM Hubbert, Jenni Fagan (recently included on Granta magazine's prestigious, once-a-decade Best of Young British Novelists list) and film-maker Paul Wright, whose debut For Those In Peril was a hit at this year's Cannes and Edinburgh film festivals.

Given all that, and awards, accolades and a prestigious publishing contract behind him, Letford's roofer-by-day-poet-by-night-tag is starting to look a little in need of a rethink. "It's a difficult thing," he says. "I can't hide from the fact that I was a roofer and I shouldn't. But I don't think that it should matter. People shouldn't focus too much on what I did. Most writers have a day job … But what people see is an arc: roofer to poet. That's interesting, but it's sad that it's interesting. It's sad that there aren't more writers - and politicians - who are coming from working backgrounds. It shouldn't be so unusual."

Perhaps, in 40 years' time, thanks in part to Billy Letford and his verse, it won't.

Framed Against The Sky is at Woodend Barn, Banchory at 6pm on October 23. The 2013 Sound festival runs until November 23; information at

01224 641122 and www.sound-scotland.co.uk