IMO Allison was not thrown from the bridge but hidden further up river in the hope that she would never be found.
My reasoning is that, according to police, her killer was someone known to her. If it was in fact someone known to her they would not dump her body out in the open, albeit under a bridge, because there is every chance that her body could be linked back to them. The murderer would not want the crime linked back to him in any way. If, for example it was a random killing and the killer was unknown to Allison, then I could understand that they would dump her body without hiding it because there is nothing to link them back to Allison.
IMO Allison was secreted further up river and her body was washed down by flood waters. IMO she was dumped in or near the scout grounds because the perp(s) knew the area. She was put there in the belief that she would never be found.
The scout grounds have invariably been ruled out by some sleuthers as being too obvious because of the BC's connection to the scout movement. IMO the BC's latched onto the Baden-Powell scout connection whenever they wanted to name drop. Perhaps they considered the scout grounds to be their property to use how they wished.
After reading a recent bio about old BP, I personally would never even let on that he was a relative. Icksay ittlelay uckfay. (That's Latin, albeit of the Porcine variety).
