As politicians outline rival visions of a green agenda, an airline has angered environmental campaigners for flying an empty passenger plane in order to keep hold of its landing slots. The British Mediterranean Airways (BMed) round-trip flights between London's Heathrow and Cardiff International have been taking off six days a week since October. They have not appeared on departure or arrival boards, none of the 124 tickets were sold and all passenger seats remained empty. And to the chagrin of green campaigners more than five tonnes of C02 has been pumped into the atmosphere on each 140-mile journey.