My colleague Matthew Tempest calls from the front of the march to report that an anarchist core broke through a fence and are now facing off against riot police who being shipped in by Chinook helicopter.
I am at the other end of the march, sat in a park, where the first contigents of returning demonstrators could not be greater. There is a cheering and clapping among those who were back earliest and still think it was a peaceful demonstration. The first to return - the clown army - played clown music and others carried banners. The nearest comparison would be a silent slapstick movie set in Speaker's Corner.
I can't imagine what will happen when news of the fence reaches the park, and what impact that will have on what has been an exceptionally welcoming and friendly town.
