I'm not downplaying the horrible events in London, but I'm always grimly "amused" by the reactions which expect that events like that put a city on lockdown, with everybody too scared to leave their kitchens or something. London's a big place. 9 million or so people live there. People gotta go to work. People still go to the pub after work. In a dense city, a mile away is like a million miles away. I lived in London years ago during a period when there were 3 nontrivial terrorist attacks, and while they were horrible most people didn't adjust their life in any way. If I heard about (for example) a bomb going off in the heart of Philadelphia (a mile away or so), I wouldn't fear for my safety at all.
9/11 was obviously a bigger deal in NYC, because it was a BIG DEAL with lingering aftereffects, but even the 7/7 bombings in London, as horrible as they were, didn't shut down the city (The London 7/7 bombings got surprisingly little attention here in the US compared to what any terrorist attack anywhere gets now, despite their scale, but that's a subject for another blog post).