THIRTEEN environmental activists pleaded not guilty of aggravated trespass in court yesterday after blocking Heathrow airport last month in protest at plans for a third runway.

Together with dozens of their supporters the activists from the Plane Stupid group staged a protest moments before entering Uxbridge magistrates’ Court, London.

Over 40 people carried placards reading “Stop Heathrow Expansion,” with some dressed in polar bear costumes and David Cameron masks.