8 December 2012 Last updated at 13:11 ET

Trafalgar Square fountains turn purple for 2012 volunteers

About 3,500 volunteers are attending the ticketed concert in Trafalgar Square

Fountains in London's Trafalgar Square are lit up in purple to honour the contribution of 2012 Games volunteers.

About 3,500 volunteers including Team London Ambassadors, London 2012 Games Makers, travel ambassadors and other Olympic volunteers were guests at a concert in the square.

London Mayor Boris Johnson said the 8,000-strong army of volunteers "proved to be the beating heart of the Games".

Volunteers may be deployed in future for major events in London, he added.

The square has been closed to the public and the concert, a ticketed event, began at 16:00 GMT.

Opera duo Jonathan and Charlotte performed at the concert along with the Centre for Young Musicians concert choir.

The mayor said: "These people were at the heart of it, they gave their heart and soul, they were fantastic. They turned the whole of London into an exuberant Butlins-type atmosphere."

Mr Johnson added that the "magenta magicians" could be mobilised for events in 2013 to help manage events like the New Year's Eve fireworks, as well as for domestic and international sports events like the UEFA Champions League, rugby fixtures and tennis.