At one point, a squad of uniformed men bearing clear riot shields walked into the camp in formation.
But it also costs money to clear up riots, savagery and antisocial behaviour.
Setting out his central argument, Cameron said: "As we begin the necessary processes of inquiry, investigation, listening and learning, let's be clear: these riots were not about race: the perpetrators and the victims were white, black and Asian.
We've steered clear of riots ever since.
Try to keep to the streets that are clear of riots, and avoid the main roads that are more likely to be occupied.
As a hooded figure stalks the glass canyons of the financial district, it's clear that rioting has already begun nearby.
Whatever has taken place on the front lines of the bridge I don't know (though I can guess) but by the time I get to the main entrance of the opera house, the road is clear of riot police and I can see that the bridge leading to Tahrir square is also full of thousands of people.
As East Coast forests were cleared, a riot of foreign weeds — dandelion, groundsel, dock — took over, promptly followed by European grasses.
The central square known as Pearl Roundabout, which had been a base for the protest movement, was violently cleared by riot police.
After the smoke cleared, the riot had caused approximately $114,000 worth of damage, two people were injured, and the cops had arrested 91 people (only six of whom were over 25 years old).
