For the American members: If it helps you picture it, Jimmy Savile was basically the British equivalent of the late, great Dick Clark. ("Top of the Pops" = "American Bandstand.") Now imagine Dick secretly banging (consentually or - often - not) anyone with two legs in sight (legal age or - very often - NOT) for decades with ABC covering his tracks and paying off the cops and you've got the idea. This is a MASSIVE scandal in the UK right now, and several more celebrities from that era (among them "Rock 'n Roll" singer Gary Glitter) may end up facing jailtime due to their associations with Savile.
I think sugesting the BBC covered his tracks and paid off the police suggsts a level of conspiracy that probably didn't actually exist.
Many factors contributed to keeping Savile out of jail, for starters as has been said, some of his actions didn't seem that out of place with prevailaing culture at the time, and even though people seemed to have suspected things, nobody ever seemed to have the proof/will to act, it seems there were isolated complaints to the police but there was never enough evidence to back up what would have been the word of a youngster against a popular tv personality who raised obscene amounts for charity, and I've heard it said that if the police had had the networks in place back then that they had now, things would have been taken further, because isolated complaints to differeing forces would have suddenly tied together and a pattern would have emerged.
A lot of people (ot just in the BBC but in the NHS, the police, government etc) turned a blind eye to what was going on, but it doesn't seem likely there was a huge overarching conspiracy.