a few days after the last election, David Cameron made a bold promise: to lead the greenest government ever. In opposition, Cameron brandished his green credentials to show the Conservative Party had changed, and prove he was in touch with young people and everyone who cared about the environment. arctic photo-shoots were hastily arranged, complete with huskies. The public were exhorted to "vote blue and go green". Eighteen months later, as Chris Huhne, the Climate Change Secretary, jets off to Durban for the latest round of negotiations, all that remains is a trail of broken green promises.  The stakes at Durban could not be higher. We have to make progress on a binding legal global agreement to cut carbon emissions and deliver on climate finance. But the omens are not good. Since the election, Cameron has failed to make a single speech, or attend a single conference, on climate change. He's snubbed next year's landmark Rio+20 conference, even though it was re-arranged to allow him to attend. In Europe, the Government has cosied up with extremists, and opposed controls on oil extracted from tar sands - a notoriously high polluting fuel, which almost every other European country wants to tackle. This, and its lax attitude to arctic drilling, are turning the UK into a clearing house for the world's dirtiest oil projects.  In the autumn Statement last week, Cameron and George Osborne showed they would rather pander to the Tea Party tendency in the Tory Party - the rump of Tories who either don't believe in climate change or don't think it's worth bothering about - than get serious about tackling climate change. Osborne revelle