Coachloads of concertgoers had braved the perilous weather for an evening of Christmas carols, classical overtures, the Hallelujah Chorus – and, of course, Frosty the Snowman. They had come to sing their hearts out, and to hear the UK’s most famous clarinettist, Emma Johnson, play a Classic FM-friendly mixture of Gerald Finzi, Ludovico Einaudi and ­Gershwin improvisations.

It’s familiar, and lucrative, territory for any one of Scotland’s professional ensembles to crowd in on. But no-one from the orchestral elite was in sight. Instead, the concert was bolstered by a crew of hard-working amateur performers – including a choir filled with hospital workers – who annually give their time and efforts to this heart­warming date on Glasgow’s musical calendar. The money raised goes to the CLIC Sargent charity, which cares for young people with cancer. Last year it received £35,000 from the Glasgow concert alone.

Besides karmic satisfaction, the Glasgow Chamber Orchestra – who accompanied the choir – benefited from appearing in front of a gigantic crowd in the city’s most illustrious venue. One of Scotland’s most active amateur groups, the GCO is often invited to play at these concerts alongside violinist Nicola Benedetti, a regular participant and well-publicised patron of CLIC ­Sargent, and the guest star at the charity’s next concert on December 16 at Edinburgh’s Usher Hall.

Charity gigs such as this are ­amateur orchestras’ bread and ­butter. But ensembles such as the GCO are also taking on the pros at their own game, with bold programming, exchange schemes with foreign orchestras, starry soloists and world premieres of contemporary works. “We’re overwhelmed by the number of musicians and ­composers who want to work with us,” says Ruth Campbell, cellist and orchestra secretary. “We now have a database to keep track of it all.”

Peter Cynfryn Jones, a BBC SSO violinist and the orchestra’s long-standing conductor, says: “I work the orchestra very hard but the ­players really appreciate that. When I listen to past recordings of the orchestra, I’m always amazed to hear how professional they sound.”

Additionally, the orchestra has opened many doors for Jones personally. “The GCO once did a project with the BBC SSO called Tandem, which led to me being involved with several educational and conducting projects afterwards,” he says.

A profile of the orchestra’s 50th anniversary back in 2006, written by The Herald’s music critic Michael Tumelty, pointed out the astonishing diversity of its membership, comprising “bird conservationists, church clerks, occupational therapists, teachers, students and retirees”. What all of them share is the desire to keep up those hard-earned instrumental skills, so often lost in the hubbub of everyday

adult life.

Campbell, a pharmacist, has been in the orchestra for 15 years and has seen a bevy of top soloists enter and leave through the orchestra’s doors. But she says its members could never become inured to working with those big names. “While Emma Johnson was on stage, I could see other players in the orchestra were completely spellbound. They thoroughly enjoy being in an orchestra that allows them to be on stage with world-renowned players.”

But it works both ways, says Linda Young from Making Music Scotland, the national association for amateur musicians. “The ­amateur sector actually puts a lot of money the professionals’ way. Our membership spends about £1m a year on employing such musicians.”

Non-professional music is now one of the biggest voluntary sectors in the whole of Scotland, with 12,000 individuals on the books of Making Music alone. This comes as no surprise to Young: “I think amateur groups really flourish up north because of the nature of the geography. There are some places which are so remote that live music doesn’t really get to them, so they go ahead and do it themselves.”

Indeed, at a time when professional arts organisations are battling recession woes, entrepreneurial volunteers are showing the way forward. Take the Scottish Sinfonia – also frequent contributors to the CLIC Sargent concerts – who will join the Edinburgh Bach Choir for a rare performance of Elgar’s Dream of Gerontius in February, with conductor Neil Mantle even discussing the hefty work in a podcast available to download from the band’s website.

Such ambitious projects require serious elbow-grease beforehand. For the GCO players, whom I have recently joined as a cellist, that means rehearsals every Tuesday evening at Caledonian University. Under the watchful eye of ­conductor Jones, we have been preparing for a winter concert bill at Sherbrooke-St Gilbert’s Church this Saturday, which will include the underrated Haffner symphony by Mozart and Rossini’s bracing Overture to The ­Italian Girl in Algiers, an inspired choice following the recent, triumphant staging of the work by Scottish Opera.

So if, as George Bernard Shaw once said, “hell is full of musical amateurs”, count me – and those thousands of volunteers – in.

The Glasgow Chamber Orchestra winter concert is on Saturday at Sherbrooke-St Gilbert’s Church in Glasgow. The next CLIC Sargent concert is on Wednesday, December 16, at the Usher Hall, Edinburgh.