I wouldn't compare these events. London riots started after a person died while being followed by the police. At night, a group of people went close to the police station and, without any intervention by the police, started burning some of the nearby buildings. Then it just went from there without any police intervention at all. If there's one thing to say about the London riots is how polite police was with the whole events.
If you recall the London riots (during which I was in Wales), rude attitude of police and political scandals were among the suggested reasons, which are also among the facts that inducted things happened here in Turkey.
http://en.wikipedia.org/wiki/Taksim_Gezi_Park