Interesting - didn't know that about the non-shaking rule. Was on a train today (Earl's Court underground) and a guard was trying to wake someone to ask them if he owned the bag that was lying unattended in the middle of the carriage. He used his radio to wake the guy up - not by knocking him gently on the top of the head but but getting it to make a very loud beep in his ear. Didn't realise he couldn't wake him more normally.