bremner: Our local Force are continuously being told to 'do something about it' but that instruction rarely comes with any, practical, suggestions. So they do what best they can.
Most of us are aware that such Posters will make little, or no, difference to the die-hards. However it may warn the more sober, if that is an acceptable pun, of us that it's a good time to keep our heads down.
While I have no Statistics to quote, I have been told by a member of the local Police Force that they reckon that most of the injured are innocent by-standers rather than the Instigators.