Was this charity run hosted by an outlaw club ? if so, this is standed proceedure, my opinion is that they want to stop most people from attending charity rides and events organised by outlaw clubs for the sole purpose of cutting off their public support. While i'm on that subject, recently in my local area a clubby won a court case ( i think the main charge was assaulting a police officer ), anyway, it was a car, bike and tatt show, the cops where harrassing everyone they could but ol' mate was clued in on the law and the cops had set up an illegal blockade, so he fronts them and after they refused to rectify the situation he starts to move or remove the witch's hats they had set up, anyway it ended in a bit of push and shove etc ....... but yeah, if its anything to do with an outlaw club expect police harrassment, i have many stories on the subject.