You may as well ask why they would assault Jody Macintyre, put Alfie Meadows in hospital, punch a fifteen year old boy, and rough up teenage girls. It is because it is their job to contain threats to 'public order', and they see violence and intimidation against selected groups of identified 'troublemakers' and 'ringleaders' as the most effective means of doing so. History would suggest that they are not wrong. That's one reason why the people who suffer from police violence and harrassment need to our solidarity. It's also why it is vitally important not to fall into the knee-jerk, at best disproportionate, denunciations of 'violence' against property. Because in doing so, you corroborate the police's narrative and alibi. You displace the proper focus on far more serious and potentially lethal violence inflicted by people who are armed and trained in its application - I don't know how bad things got tonight, but they are going to kill someone one day if things continue in this direction. And you thus assist the weakening and intimidation of your movement. Earlier today, I was listening to a policeman complain to a member of the public that people confuse the police with the government, and forget they're public sector workers. I thought, but did not say, that it's easy to forget when the police spend all their time attacking the government's opponents with big sticks. On which note, this is doing the rounds on Twitter: "Unconfirmed reports that forces loyal to Cameron are attacking rebels in Trafalgar square."