Soccer and Violence

Kevin Drum has a question on his blog, Why is Soccer so Violent?
http://motherjones.com/kevin-drum/2010/06/why-soccer-so-violent

What the average American doesn't understand is the role of class in the rest of the world. Drop yourself in the middle of London. Largely white anglo-saxons right? Wrong! Every last one of them are constantly calculating the class of all the other ones.
Ask for directions. The accent of the speaker is referenced against a hundred types and regions. Oxbridge. Scouse. Midlands. Cornwall. Glasgow etc. And everyone of these people has an allegiance to a football club.
I won't get into all the shades of the London clubs and their followers but point to the classic rivalry of Rangers and Celtic FC. Catholic and Protestant in a town where Culloden is still remembered today.
Once upon a time it could get you killed!