Guardian: They are young, smart, organised, committed and, if they are allowed to have their way, they would like to save the world. No longer is an environmentalist a geeky elderly man in socks and sandals or a dreadlocked traveller in a rainbow jumper. Britain’s new vanguard of eco-warriors are predominantly in their twenties, they are articulate and knowledgeable and techno-aware. Monday’s demonstration by 57 young protesters from the environmental group Plane Stupid at Stansted Airport in …