In essence, he is accused of being a paedophile who preyed on pubescent girls but it wouldn't surprise me if the gender didn't matter to him that much.
It is alleged he was a facilitator (i.e. pimp) for many very senior establishment figures who shared his proclivities over many, many years. This was, apparently, one of the reasons he got away with it. As indicated in a post above, it was a case of "I go, you go". He would have been much more subtle than that, of course but it seems he cultivated relationships with the elite and catered for their perversions where he could. He knew friends in high places would keep him out of the papers and out of jail.
Google Jimmy Savile and Edward Heath and start following the trails. Where it takes you will make the hairs on your neck stand on end. You'll have to filter out some of the stuff that is clearly delusional bollocks but what is left is a very sinister story of depravity perpetrated by a lot of famous and powerful people.