Thousands of people are on Thursday expected to descend on Heathrow in what BAA, its operator, fears could lead to a day of chaos and disruption at London’s busiest airport.

BAA has already gone to court in an attempt to stop the militant group, known as “passengers”, from reaching the terminals. It says the smooth functioning of the airport will be badly jeopardised if the passengers are allowed anywhere near the sites. A spokesman says the airport runs like clockwork when the travellers are kept away but when they arrive the scene rapidly descends into chaos.