The green website grist.org praised the star of The Other Boleyn Girl for her campaigning work for the protection of Rwandan gorillas and as the face of an energy-saving lightbulb. She was also commended for the launch of a vegan shoe range.
Other film world celebrities to get the eco nod of approval are Leonardo Di Caprio, Cameron Diaz, Brad Pitt and Julia Roberts.
In the grand Hollywood tradition, it seems British stars are the villains of the story. Celebs named as the least eco-aware were David Beckham, for all those transatlantic flights, his wife Victoria and the rest of the Spice Girls for their use of private jets, and Liz Hurley who flew 250 guests to India for her wedding.