More than 50 climate change protesters were arrested today after breaking into Stansted airport and forcing the cancellation of scores of flights.

Graduates and professionals were among those detained after what one activist called “designer direct action” at the airport by the campaign group Plane Stupid.

With the public inquiry into the expansion of the Essex airport due to open next Spring, and a verdict on a third Heathrow runway expected in January, campaigners gave warning that direct action could become a recurrent problem for airlines and their passengers unless the sector’s growth is checked.

Thousands of passengers had their travel plans thrown into chaos after activists cut through the perimeter fence at Stansted and set up camp on a secure part of the airfield near where aircraft taxi to the runway.

Times Archive, 1967: Stansted protesters

The demonstration began at Stansted itself, when a specially chartered train filled with 400 local people pulled out for London

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BAA, the airport operator, said it would learn any lessons that emerged from the breach but the GMB union, which represents workers at Stansted, revealed it had already been pressing for a security review because of concerns over the state of fencing at the airfield.

Ryanair, Stansted’s largest airline, cancelled 52 flights and called for an investigation into why BAA had failed to keep the airport “secure and open”, describing the disruption to passengers as “unacceptable”.

Police officers arrested 56 people, including undergraduates, postgraduate research students, a film animator and a hat designer, after breaking up the protest.

The activists, some of them travelling in an old fire engine, had arrived at Stansted shortly before 3am yesterday, while the runway was temporarily closed for maintenance work.

The protesters, some wearing high visibility vests which have the message “Please DO something" printed on them, chained and locked themselves to security fencing that they had brought with them, forcing police to physically remove them.

Lily Kember, 21, a third-year anthropology student at Edinburgh University, said the group used bolt-cutters to get into a secure area around 55 yards (50m) from the runway.

Ms Kember, a former private school pupil from Kensal Green, northwest London, said: “Being arrested is a terrifying prospect, but not nearly as terrifying as the threat of climate change.”

Her mother, a primary school teaching assistant, told reporters: “We know what she does and we stand by her.”

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