There was an eruption of gang warfare at en event at the Rockbourne youth club a year back or so, but it was all about kids from other areas coming for a ruck.
I think, to some extent, these things come in cultural/identity cycles - it was before my time, but think back to the fights between the mods+rockers. Imagine if hooded youths went for fights on the seafront today! The DAily Mail would have a heart attack, and encourage all its readers to move out immediately!
Factors that contribute to bad behaviour of kids today are:
-Confised identity
-Breakdown of family
-Imported US stupidity
-Poverty
-MAterialistic culture, post-Thatcher, no such thing as society, etc.
SE23 youth aren't too bad at all - thats because, as we all know, SE23 is an oasis of peace and goodwill in London!