Last year at Heathrow, I got selected for a "random screening" where they take everything out of your luggage and scan every piece individually through the x-ra

Last year at Heathrow, I got selected for a "random screening" where they take everything out of your luggage and scan every piece individually through the x-ray machine again. It takes me half an hour to pack my luggage, so the process took a while. I was not pleased that morning. (Amusing side anecdote: There was a group of mexican school kids passing through security at the same time. Some were also selected for random screening. The random screening lady was from Spain, but she told them the policy (law?) dictated she only speak to them in English even though everybody involved in the transaction spoke Spanish better than English.)