Worst of all for the sake of the long hours of flying, no carryon luggage means no books, no game boys, no laptops, no knitting, no magazines, no notebooks. It means spending the long hours of a long-haul flight being bored, and being on a plane full of other equally bored people, adults and children alike. In-flight entertainment systems usually take a few hours to start up at the beginning of a flight. A flight full of bored, fidgety people. At least there's one form of entertainment this will encourage, although just how successfully entertaining it is depends on luck of seating: conversation.
I realize that boredom seems a small price to pay for security, and a small factor indeed in the face of today's rescheduling, cancellation, and 2000 persons of customs backlog at Stansted. But next week and the week after, when I will be travelling, boredom is likely to be a greater risk than all the other mess which today's headlines unfold.