The demonstration, which began at 5.40am and lasted around five hours, meant dozens of flights were cancelled while incoming planes were diverted to Gatwick and Southend airports.

The incident triggered safety concerns amid reports the demonstrators bypassed security by sailing a blow-up dingy across the Royal Docks.

Police arrived at the airport minutes after the demonstration began but it was several hours before any arrests were made. Scotland Yard said they had to wait for ‘specialist resources’ needed to unlock the protestors.