Also what OP seems to have forgotten is that protocols vary significantly from one airport to another (even from one terminal to another at LHR). Some airports want the liquids bag in a tray on their own, some want Kindles others don't, and someone even mentioned taking shoes off, which I haven't done at T5 for many years. It's all very good having loads of signs, but most of us are too busy coping with looking after our goods and chattles and the particular protocol applicable to lane 4 at T5 North at 08.30 on a Saturday morning to read all the signs.