The famous Piccadilly Circus lights in London were switched off for the first time in 68 years yesterday in support of a climate change event.

|PIC1|Londoners turned off their lights in Thursday's blackout to raise awareness of global warming. Landmarks such as Buckingham Palace, the Houses of Parliament, the BT Tower and City Hall also took part in the campaign.

All six advertisers at Piccadilly Circus switched off, the first time since 1939 when they went out for the blackouts at the start of World War II. They were then switched back on in 1949.

The aim of the campaign was to have all non-essential illuminations turned off between 2100 BST and 2200 BST, according to organisers Lights Out London.

If London's three million households were to switch off their lights, the city could save 380 tonnes of CO2 in just one hour, enough to fill more than 2,000 double-decker buses or the Royal Albert Hall twice, organisers have said.

The event was based on Earth Hour, a similar, hour-long mass switch-off earlier this year in Sydney that involved 65,000 households and 2,000 businesses and landmarks, including the Opera House and Sydney Harbour Bridge.

Lights Out London, organised by the radio station Capital 95.8FM, is supported by Friends of the Earth.

Jenny Bates, from the environment group, said: "The majority of the capital's carbon dioxide emissions come from buildings, so switching off lights and appliances that aren't needed can play a significant role in tackling climate change.

"And it can save you money too," she added.