"Could it not be that it was originally launched in order to search out & name known Paedophiles & bring them out into the open to be dealt with by the authorities but somehow lost its way?"
Well that a novel interpretation.As best I can tell they were an organisation set up with the express intent of legitimising the notion of sexual relationships between children and adults, and lobbied on that platform, including lobbying for a change in the law surrounding incest etc. So no, I do not think they were set up with the intent of catching paedophiles.
http://en.wikipedia.org/wiki/Paedophile_Information_Exchange
I do find it odd they were able to exist for a decade or more, and may even have been the recipient of government grants though. I think PPs comments about the times and the debates going on at the time to be quite illuminating though.