... and the lights all went out in ...Paris, Rome, Madrid, Athens

The lights of Paris dimmed for five minutes on Thursday in a nationwide "lights out" campaign, aimed at raising public awareness over global warming.

The Eiffel Tower, lit by 20,000 bulbs, also went dark at 1955 (1855 GMT).

During the switch-off, the power grid operator RTE observed a fall of 800 megawatts, representing just over 1% of France's total consumption.

Several other European cities also staged symbolic blackouts. In Rome, the lights of two of its celebrated monuments, the Colosseum and the Capitol, were turned off.

In Spain, Madrid's Puerta de Alcala arch was plunged into darkness.

In the Greek capital, Athens, lights illuminating several public buildings - including the parliament, city hall, and the foreign ministry - went dark.
BBC:

... and what happened in Britain? That's right - bugger all!