What the hell is going on with security guards cracking down on photography in this country? I'm reading stuff like this on an increasingly regular basis, and it's getting a bit worrying.
UPDATE: Sean has linked to a petition at the Downing Street website in the commments below. Well worth putting one's name to that, I think.
In answer to Tim's question, I believe 'street photography' is when one makes pinhole cameras out of used crack vials, then sells the resulting happy snaps to the Observer magazine. Hope this helps, Tim.