> As someone who used to organise large demonstrations in London for CND [a UK anti-nuclear org] a long time ago -- there is no point that the crowd is ever so

> As someone who used to organise large demonstrations in London for CND [a UK anti-nuclear org] a long time ago -- there is no point that the crowd is ever so large that a combination of the organasition itself with the police where the crowd "should" be unable to control it. In fact when you're putting together a demo in London you meet the Met police and meeting that requirement is one of the things you discuss with them. It sounds like that depends on the police and protesters being at least nominally willing to cooperate, however grudgingly. That's not always the case. If the police and the local government think that the protesters have no right to be there at all and the only thing preventing open violence is the fear of bad publicity, it's a lot more of a powder keg. If the protest is about police violence, for example. Have a friendly advance chat with the police about where, when, and how many, and you'll likely show up to find your venue packed with concrete barricades and cops in riot gear to "preserve public safety". You need to get a critical mass of protesters in place with cameras on them before the cops can get fully organized, or they'll shut you down before you can begin.