Certainly the inquiry report into the various failures to prosecute Janner does make terrible reading. None of it though seems to me to scream of deliberate cover-up.
https://wikispooks.com/w/images/2/2a/Henriques_report_190116.pdf
TL:DR - Overworked cops and lawyers making bad decisions based on bad guidelines with of course the ever present knowledge that this was an MP being considered for prosecution and if a conviction did not result, their careers would undoubtedly take a permanent nose-dive.
The report into Smith seems likely to uncover much worse in the way of cover-ups.
