Tanyabranning I agree with everything you're saying.
Until recently I lived in Brixton, if I had a pound for every time a friend said they wouldn't come see me because it was too dodgy... 
I don't know Tottenham (lived in Finsbury Park though) so I can't comment on the specifics there.
But people should remember that when things like this happen and you watch the news, you are only getting a snapshot of the community and also a narrative that the police and government want to put forward. You're not seeing the countless times that totally innocent people have been harassed and treated like shit by the police before this. You're not seeing the miserable conditions under which thousands of hard-working people live.
I'm not excusing the violence and looting, it's despicable. But surely our top aim here is not merely to judge, but to prevent it from happening again? In which case we need to really understand the root causes of the initial disturbance, which is what allowed things to degenerate to the point that criminal opportunists took over.
It's crazy to me that we are putting so much effort into understanding the dynamics in Helmand that lead people to join the Taliban, because we realise this is the only way to make any progress, but we're not willing to apply that same logic to our own cities.