Of course 10 jurors convicted after DS Jones pretty much single handedly shored up the evidence that convicted JB: silencer and JM's testimony.
What motivated DS Jones? Did he genuinely believe JB was guilty or was he incentivised by JB's extended adoptive family who went on to inherit the Bamber's 500k estate which they wouldn't have done had JB not been convicted.
No idea what you mean by Julie and the boys?
I have wondered what motivated Stan Jones too. Pure speculation, but he might have taken offence at Jeremy's actions/reactions after the murders, then been influenced by what certain people had to say about the sort of person Jeremy was. He might have felt a little cheated at the thought that, if Sheila was the killer, nobody would "pay" for the crime, as Sheila was dead. He might have thought his superior was messing things up, and that he could do better.
We aren't ever going to know for sure.