Those at 'the Beeb' knew. The Royal family knew. The Prime Minister knew. Of this I have no doubt. In turn, I expect Jimmy Savile knew plenty of secrets about those in positions of power. It's how those with money and influence operate.
The general public, on the other hand, knew that Savile was eccentric but had no idea just how depraved the man was. He hid his evil acts behind a carefully constructed smoke screen that, as this documentary puts it, made him look like Jesus crossed with Father Christmas.
Part one of this two-part look at the monster that was Jimmy Savile talks about the DJ/TV presenter's rise to fame, his public persona, his charity work, and his close ties to those in power. It tells us very little about his secret, darker side, only hinting at his attraction to young girls in the final few minutes. That really is just the tip of the iceberg...
In fact, much of what we see in part one could have been left on the cutting room floor: it's not very informative or particularly interesting. I imagine those most viewers are far more interested in the details of Savile's deviancy that I expect part two will deliver, so unless you have time to waste, I suggest skipping straight to the next episode.
That said, this is just about worth watching to see Selina Scott squirm in embarrassment at her TV appearances with Savile.