The 2012 Games are a once-in-a-lifetime opportunity for London to boost grassroots participation in sport, and it must not be allowed to slip away. That was the message that came across loud and clear at last night's heated debate on the Olympics, hosted by this newspaper.

Lord Coe, athletics medallist and chairman of the London Organising Committee for the Games, took on sceptical columnist Will Self over the event's potential to motivate and inspire young people to take part in sport, even when they will never reach the heights attained by the most gifted. Just as thousands of Saturday morning seven-a-side amateurs are spurred on by images of football's greatest names, and during Wimbledon every park tennis court is packed, so the Olympics can galvanise young people to take part in sport.

So the opportunity for this city to use its hosting of the Games to motivate young people must not be missed. The challenge is not just to get the Olympic park buildings ready, or boosting regeneration of east London, vital though these goals are. The Mayor can take a lead on boosting participation, as he has with his appointment of former sports minister Kate Hoey. But in most cases responsibility for provision of sports facilities rests with local councils. For too many, maintaining sports halls, swimming pools and playing fields is seen simply as a cost to be reduced at a time of financial pressure. At worst, pools have been closed and fields sold to developers.

Town halls need to be far more imaginative about the 2012 opportunity and work with the enthusiastic and often utterly dedicated volunteers who run the South-East's sports clubs to find out how they can help. Schools and parents need to make the most of children's likely interest in what will be 2012's biggest event by far. Councillors and headteachers who do not see the potential to attract children into sport are missing the best chance they may ever have to draw young people away from anti-social behaviour and the dangers of obesity and ill-health. We still have four years, but the clock is ticking.