Singer KT Tunstall performs at Westfield London after switching off their Christmas lights to launch the countdown to WWF's Earth Hour 2012.

KT’s performance also marks the launch of WWF’s nationwide competition to find a community, which will lead the Earth Hour switch off in the UK. WWF's Earth Hour is the world's largest environmental campaign, which sees people, communities and landmark buildings switch off their lights for one hour on 31st March 2012 to celebrate and show concern for our planet.

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