Why would they keep it secret from the families and children unless it's doing something nefarious?
They're not keeping it secret. It's the same sort of thing as all the EULAs/T&Cs we have to click agree to: much too boring to pay attention to, unless it's a headline.
That said:
> How long we will keep your personal information?
> We will hold this information for as long as it is needed, or if we are required to do so by law. In practice this means that your personal information may be retained for the relevant period listed below:
> • Integrated family Support (1772), 75 years
- https://www.bristol.gov.uk/files/documents/5977-insight-bris...
How on Earth is 75 years a legitimate duration for any of this information?