From the article:
Numbers are all important in a riot and the tipping point comes when the rioters feel in control, he adds.
"You cannot riot on your own. A one-man riot is a tantrum. At some point the bigger crowds confronting the police realise that they are in control."
"Humans are the best on the planet at imitating. And we tend to imitate what is successful. If you see that people are walking out of a shop with a widescreen TV and trainers, a certain kind of person thinks why shouldn't I do that?"
Workman argues that some of those taking part may adopt an ad hoc moral code in their minds - "these rich people have things I don't have so it's only right that I take it".
For most, the motivation is the thrill, with the "free stuff" just a bonus. But not for the ringleaders who manipulate the mob to target high-value shops.
"If you compare it to the riots in the 1980s, there's a lot more stuff you can loot easily, such as portable electronic gadgets, mobile phones and flatscreen TVs.