boxy, it's not at all clear the the BBC turned a blind eye, at least not yet it isn't. People said they'd heard rumours but nobody had any facts to hand. None of the victims seems to have reported it at the time.
It's hard to say what anyone might have done about it. Journalists who'd heard rumours could have tried to investigate them (and that's not just the BBC, of course, it's all of Fleet St, which may be why they're trying so hard to point the finger at the Beeb) but anyone who asked got nowhere at all.
The fact that some of it happened on BBC property doesn't prove any sort of BBC complicity. You'd have to show someone somewhere actually knew what was going on. So far nobody's shown anything of the sort. Just ugly rumours.