Thousands of activists block London roads to demand action on climate change

The protests are being led by the British climate group Extinction Rebellion and will involve demonstrations in 33 countries around the world over the coming days.

"I realised that signing petitions and writing letters was not going to be enough. Real action is needed," said Diana McCann, 66, a retired wine trader from south London, holding a banner in the middle of a traffic-free road. "It's like a world war. We have to go on to a war footing."