Policing of the airport is the responsibility of the aviation security unit of the Metropolitan Police, although the army, including armoured vehicles of the Household Cavalry, has occasionally been deployed at the airport during periods of heightened security.
Full body scanners are now used at the airport, and passengers who object to their use after being selected are not allowed to fly. These display passengers' bodies as a cartoon-style figure, with indicators showing where concealed items may be. The new imagery was introduced initially as a trial in September 2011 following complaints over privacy.