@JtP - This is what you wrote
"It's rather easy for us to sit here in 2013 and tut tut about how victims have selfishly (that is the implication isn't it?) not come forward to pres charges."
That sounds like a kind of inclusive "us" to me. Without going back from all the contributors, I can only comment specifically about my own comments and the flavour derived from those others.
None of us can know for sure that, had one of those parents who knew about an incident and then did not report it to the police, Hall would have been investigated, arrested and convicted = but it is certainly possible, particularly if more than one of the parents had reported it. And had that happens, it is likely that at least some of the victims would have been spared his ministrations. That just seems like a pretty factual assessment to me.
I remain puzzled as to the motivations of those that did not report. I do not impute a motive to them.