Guardian: London fashion week has not officially started yet but designers know that to get even a sniff of media coverage for their new collection they have pull off something special. Guerrilla catwalks no longer make the cut. Today it was an international trade lawyer wearing a chic emerald dress that set the camera motors whirring, as Miriam González Durántez, wife of the deputy prime minister, Nick Clegg, became the unofficial poster girl for sustainable fashion. González Durántez was …