Many who enjoyed Annie Griffin's scurrilous film about the media at Edinburgh's arts jamboree, Festival, were particularly struck by its bold soundtrack of summery Mediterranean brass, which was both fitting and yet entirely not an obvious ingredient.

That music was by composer Jim Sutherland, a man whose frontline involvement in Scottish music dates back well over 20 years but whose name is usually recognised only by the cognoscenti. This weekend, the pan-European musical caravanserai that has grown from his work on that soundtrack makes its Scottish debut at Big in Falkirk, Scotland's international street-arts festival, in just the second public step of what is envisaged as a long musical journey.

Sutherland's outfit is a 100-strong marching band, an outdoor orchestra called La Banda Europa whose instrumentation is indisputably unique and whose repertoire, specially written by himself, is entirely original. The 40-minute piece, which was premiered on Tyneside a fortnight ago and will be heard at 4pm tomorrow and 9.45pm on Sunday, is entitled Before the Wolf, a reference to the pre-musical formalism origins of many of the instruments involved - "wolf" notes being those outside the tempered scale.

None of which Sutherland could have foreseen when, at Griffin's behest, he tracked down the Semana Santa band in Seville and discovered that their bugles were played a quarter of a tone above concert pitch, just like the Scottish bagpipes.

"The band were unlike anything else I'd heard and their organisation is a religious Catholic mafia, a group of young men from one of the poorest areas of Spain. They rehearse in an industrial warehouse with pictures of the Madonna on the wall from 10pm. It was midnight when I had my first meeting with them."

Sutherland, whose wife is Spanish, was able to persuade them to take part in the project, combining their sound with that of the Drambuie Pipe Band, whom he marched into the studio to cheers from the Spaniards.

Sometime later, at a Musicworks industry seminar in Glasgow organised by events company UZ, who also created Big in Falkirk, UZ's artistic director Neil Butler heard Sutherland explain how he would like to expand on his work for the film soundtrack to create a truly European orchestra that combined the sounds of regional instruments into one single bridge-building entity. Butler interested the various producing partners of In Situ, which creates street performance work to tour internationally, and Sutherland secured a Creative Scotland Award of £30,000 to work on the music. Suddenly his notion was looking very real.

"I'm a person who often has ideas above his station," he says. "There was this awful realisation that I'd have to do this one. But I needed to get my teeth into something and develop my writing. This was a chance to develop something more substantial." In fact, Sutherland's career includes some highly significant milestones. He was (with Norman Chalmers and Rod Paterson) one of the founding members of The Easy Club, a band that revolutionised the playing of Scottish traditional music, its swinging style propelled by Sutherland's bodhran and cittern playing. Enthusiastically endorsed by Hamish Henderson, his musicianship was sought by Scottish film and theatremakers and he travelled the world, learning about other indigenous musical cultures until Jimmy Page and Robert Plant sought him out for their post-Led Zeppelin world-music experiments. After that he was signed to Sony as a songwriter and part of The Lanterns, a jazzy dance group that featured the singing of Gina and Sylvia Rae. These days, his other work includes production for a new Edinburgh rock band, Alfonso, and continuing filmwork, most recently on the Gaelic feature film, Seachd.

Putting together the combination of musicians he wanted for La Banda Europa has been a mammoth task, and new discoveries and destinations make it bigger all the time.

"I was aware of musicians all over the world, and MySpace is an amazing networking tool for musicians. I did a lot of cold calling. It was very difficult, for example, to find a lambeg drummer who was open to working with a bunch of devout Catholic bugle players from Spain. That traditional skill has been totally overwhelmed by politics."

Spain has also provided bagpipers and percussionists from entirely different Asturian and Galician traditions with entirely different techiniques, and there is a quartet of hurdy gurdy players from France playing instruments of different pitches and a similar ensemble of Swedish musicians on the not-dissimilar nickelharpa.

Then there's the Armenian dukuk, a sort of folk oboe, and the Spanish dulvaina, which is a little like the more often seen Breton bombard. From Serbia, there's a gypsy-style trumpet player and a bagpiper (there are also Northumbrian, Dutch and Turkish pipes) and Austria provides a klezmer-style freebass accordian and two sopranos from the Vienna Boys' Choir.

In many cases, Sutherland had to learn about the range and capabilities of the instruments from scratch to write for them, and he was careful to work within the cultural styles of the instruments - allowing the players to use their own grace notes and ornamentation - as well as melding them together in his aim to have all these "different European cultural voices speaking together as one voice".

At the same time as he was e-mailing parts to musicians to explore what was possible, they were finding new capabilities in their instruments through his writing. It has been an exercise in making music overwhelm politics rather than the other way round.

Where the project might go from here is limitless. "I'd like to broaden the band in future," says Sutherland, with no hint of irony. Through the In Situ network, invitations are coming in from Bergen (for which Sutherland wants to incorporate the hardanger fiddle), Graz, and Marseilles. Invitations to Spain and Holland are in the pipeline and there's the possibility of working with the whole of the boys' choir in Vienna.

The organisers of next year's Uefa Cup are interested in the orchestra and, of course, there's the Olympics and the Commonwealth Games beyond that. "It seems like anything can happen," says the leader of La Banda Europa. "Just a year or so ago this was just a dream."

  • La Banda Europa play Before the Wolf at Big in Falkirk tomorrow and on Sunday. www.biginfalkirk.com.