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.

“Two weeks before our action took place, the Airports Commission issued a recommendation to build a new runway at Heathrow Airport,” the accused said in a statement.

“Some of us are local residents and the existing air traffic from Heathrow is already having a hugely negative impact on the local community by way of noise and air pollution and blight on the area.

“It is critically important that climate change is prominent in the context of any discussion about the future of the aviation industry.

“Against this background and the failure of democratic processes, we believe our actions were reasonable, justifiable and necessary.”

Six women and seven men between the ages of 23 and 67 were charged with aggravated trespass and entering a security restricted area of an aerodrome.

“We didn’t want to do this, but we had to,” said defendant Ella Gilbert.

“If the government won’t prevent catastrophic climate change, ordinary citizens have to step up. You can’t reduce carbon emissions and build more runways, it’s plane stupid.

“There is already more than enough aviation capacity for ordinary people who take their one holiday abroad a year.

“Airport expansion is for the 15 per cent of wealthy frequent flyers who take 70 per cent of our flights.“

On July 13, the activists allegedly cut a hole in a fence and chained themselves to railings on the north runway of Heathrow airport causing the cancellation of 22 flights.

They were arrested at the scene and released on bail on the condition that they would not enter Heathrow Airport or its perimeter.

A supporter who wished to only be known as Margo said she came to court to “support the amazing, brave activists and to show my solidarity with them.”

The case is expected to last two weeks, with each defendant set to give evidence.