Policing demonstrations.

The Home Secretary has decided that the use of water cannon is not an appropriate response to the "student" violence.  Quite right I think.  The problem is that you are dealing with three types of demonstrator - the ones who simply want to make their point by shouting slogans and waving placards, the ones who perhaps start out that way, but then get caught up in all the excitement and end up doing things they might later regret, and finally the ones who simply came for a chance to fight the police and cause as much damage as possible.  Water cannon will not be able to differentiate - only police on the ground can do that, and we should support them in doing what is a very difficult job and accept that they will occasionally get it wrong.