A slight frisson of fear ran through us just as we were about to take off from Gatwick. A lone passenger stood up and demanded to leave the plane. His sudden departure sparked an unscheduled search of overhead lockers – in case he was a terrorist and had left an explosive device on board, I presume. The airline staff opened every locker, matching each bag to the remaining passengers. “Why are they only searching half the plane?” hissed my worried friend, not realising that while one worked from the front to middle, her colleague was working from the back of the plane to middle. Dave did not move – he’d…