Last week I reviewed a BBC SSO concert in the series entitled Afternoon Performance, where concerts are recorded for broadcast on Radio 3.

It featured a programme that, from an intellectual point of view, was challenging and ambitious. There were six works on the programme and every one of them was by Stravinsky (pictured). Now that alone would be enough to put some music lovers off: Stravinsky is not everyone's cup of tea. The works were drawn from across the immense span of the composer's career from the early years of last century, before his breakthrough with The Firebird, to about 1960.

Some of those works are very little-heard, including Capriccio (in effect a piano concerto) and an extremely advanced and tough piece entitled Movements For Piano And Orchestra. So uncompromising in its use of serial technique and pointillistic effects is Movements that Stravinsky expressed his own amazement at having done it. I know my way around Stravinsky's music a bit, but not only had I never heard Movements, I didn't even know it existed; and the BBC SSO have no apparent record of the band ever having played it.

Well, there will be opportunities in the future to revisit the piece, because the SSO, conductor Ilan Volkov and pianist Steven Osborne, who was the soloist in all of them, took them, along with the Concerto In D For String Orchestra, back into the City Hall last Saturday and Sunday to record the lot for Hyperion.

But the concert itself is worth thinking about. It was an extremely good turnout for such an uncompromising affair, the audience numbering about 400. The BBC used only the downstairs area of the auditorium, so it was busy and buzzing with anticipation: any concert with Osborne as soloist guarantees a touch of excitement; he has such a following in his native Scotland. And nobody doubts his presence was a principal reason for such a big walk-up on the day.

But it's also the case that the BBC SSO has established an important niche for itself with this Afternoon Performance series, in which there are, on average, about six concerts per season. They are full, two-hour concerts between 2pm and 4pm. The series has been running for six years, since the City Hall reopened following comprehensive refurbishment.

There's nothing brand new in the series as a concept: the BBC SSO has given afternoon or lunchtime concerts before in a variety of venues, including the former RSAMD. And those of us old enough to remember will recall the regular lunchtime series in the Henry Wood Hall, though, to be frank, the BBC SSO then was not the powerhouse band it is now: it was just beginning, in the early 1980s, to limp back from the depleted and decimated state it had been left in following a notorious attempt to disband the orchestra.

A crunch point arrived when the BBC moved out of its old west-end building and the orchestra was relocated, lock, stock and administration, to the elegant new City Hall. What might have been a challenge, or even a dilemma, was seized on as an opportunity to launch the afternoon series of concerts.

It began modestly, but within three years, SSO director Gavin Reid reported an "astonishing" 70% gowth in attendances. They're not all tough programmes, and they don't all sell as well as last week's Stravinsky event. But the series now has a niche in the diaries. It tends to attract an older audience, which raises another point.

All the orchestras and musical organisations are pushing to recruit new, younger audiences. But there's an older audience too, increasing in size as we live longer. The SSO is tapping into the daylight concert landscape. And it offers a nice wee soup and sandwich-type lunch as an hors d'oeuvre, as do the Royal Conservatoire of Scotland and Westbourne Music at their own lunchtime concerts. The whole development is a quiet and unsung wee social phenomenon, enriching, just a little more, Glasgow's cultural fabric.