The announcement of London as the host city for the 2012 Olympics wasn't the only thing that happened nearly two years ago. The next day, four bombs went off on the city's public transport, killing 52 people. After the bombings were unsuccessfully imitated two weeks later, police armed with large guns were stationed at many railway stations, watching passengers enter and leave.
Yesterday, after the recent car-bombs in London and Glasgow, I saw heavily armed police again at one station. It probably says something strange about how my mind works, but I'm instinctively more disturbed, if not scared, by the visible guns than the thought of possible bombs. I wonder whether it would be any different if Jean Charles de Menezes hadn't been shot 2 days before I first saw them.
(I could offer 10 points for guessing which station I saw the police at, but there are already points on offer for naming that station.)