Cara Delevingne and Russell Brand among famous faces protesting at the London Climate Rally

Despite running a hectic modelling career, having meetings with X Factor's Simon Cowell about branching in to music, and landing the lead role in Paper Towns, Cara Delevingne managed to find the time to do her bit to save the Earth.

The 22-year-old was protesting with a group of friends in a leopard print onesie and gorilla mask at the London Climate Rally on Sunday.

She took to Twitter to post a photo of herself and a group of friends outside Big Ben wearing animal prints and waving their placards before uploading several shots of feminist protestors, children with placards and a video from the days event.

Saving Mr. Banks actress Emma Thompson was holding up the front line outside the Houses of Parliament alongside fashion designer Vivienne Westwood and musician Peter Gabriel.

The Greenpeace ambassador questioned David Cameron's environmental policies as she marched with a sign reading "David Cameron is this your idea of a clean planet?" before taking to the stage to address the 40,000 strong crowd.

She said: "Climate change has been a bit like everybody playing a deadly game of grandmother's footsteps for the last 20 years, now this climate change grandmother has turned around and started running towards us.

"It's touch and go whether we're going to survive what we've done."

Also among the crowd was comedian Russell Brand who was sporting face paint for the occassion.

The 39-year-old didn't seem to be dwelling on his break up with Jemima Khan as he mingled with the crowd and posed for photos with protestors.

The London rally was one of 2,000 events scheduled ahead of the United Nations climate change meeting in New York on Tuesday.