I often used to wonder why nobody stood up and questioned the lyrics in his songs. It was quite obvious he was a weirdo.
Which lyrics did you question?
In the programme there was a line about 'what your mama don't know', which thy made a lot of. But Suzi Quatro had a song at about the same time with those lyrics (a different song) and there is no suggestion that she was in any way suspect. Also, the Glitter song wasn't a single, as far as I know, and the chances are that few of his fans would have been album buyers. Most of his songs didn't have much by way of lyrics - they were chants, really.
I think that after the event people say they knew all along, but rarely have anything to substantiate that. Many people did know about Saville (there is evidence that people reported him to the police, the BBC and hospital authorities), which is why the scandal went even deeper than the crimes themselves, and why I think that programmes about him are important, as they hold the various institutions to account and make it less likely that something like that will happen again.
My point upthread is that the Glitter programme didn't scratch the surface of a cover-up, if indeed there was one. It's always easy to look back and scrutinise tiny bits of video with the knowledge of hindsight, which is what I see the programme as doing. We were no wiser about whether he got away with it because 'times were different', because he was able to hide behind his persona, because people didn't believe women and children, or because he was too big to knock down and people covered for him. For that reason I think the programme was pointless - not because we need more salacious details, but because the only point of going over something like that is to understand how it can be prevented in future.