Boris Johnson hailed the Olympic volunteers for transforming Britain's capital into an "exuberant Butlins-type" atmosphere during the Games.

The Mayor of London saluted the gamesmakers, Team London ambassadors and travel ambassadors who did their bit during a Christmas carol concert in their honour at Trafalgar Square, central London.

An audience of 3,500 volunteers was entertained by Britain's Got Talent pop-opera sensations Jonathan and Charlotte, who performed hits such as Rule the World, and the Centre for Young Musicians concert choir.

And the square's famous fountains were lit up in purple and magenta, the colours of the gamesmakers' and Team London ambassadors' uniforms.

Mr Johnson said: "These people were at the heart of it, they gave their heart and soul, they were fantastic."

"They really were magical, they changed the atmosphere - everybody commented on it, on the unexpected friendliness you don't normally associate with us Brits," he added. "They turned the whole of London into an exuberant Butlins-type atmosphere."

Volunteering was one of the major successes of London 2012 and provided a welcoming face of the Games to millions of visitors to Britain.

Mr Johnson described his 8,000-strong team of ambassadors as "magenta magicians" and said that, in the light of their success, they would be mobilised again next year.

They are expected to be deployed at events such as the New Year's Eve fireworks display, the Uefa Champions League final at Wembley and international rugby games.

"Our message is 'do something great for your city in 2013'," Mr Johnson said.