All of the evidence suggests that the looting/rioting was in many cases controlled by the gangs. Obviously others were involved but there has a clear hierarchy with the big boys getting first go at the loot after they arranged for the windows to be put in.
i havent seen evidence that that was the case over and above what common sense would dictate (ie the hardest people with the biggest rep would probably have got first pickings)
i think this whole gang thing is a distraction that appears to be confusing some kind of new class formation with fashion - in my day there were football firms, biker gangs, a few organised criminal gangs, and lots of bunches of bored kids who hung out together, got involved in petty crime, looked out for each other and fought together
these days we'd probably have given ourselves a name and been a gang, back then we were just a bunch of mates