Sounds to me the whistelblower might be the forum's 'Bill' who claims to have been a serving police officer with Essex constabulary.
Not me, I didn't blow any whistles.
The article is pretty much nonsense; Unfortunately, they lead off with a huge error; "Jeremy Bamber's 40-year bid to prove he is innocent of the White House Farm murders has received a significant boost after bombshell claims by a police whistleblower that
officers tampered with the crime scene to place Bamber in the frame for the killings". No, they didn't.
Jeremy was not suspected of any involvement in the murders until weeks after the 'tampering' with the crime scene so anything that was done on 7/8th August can only come into the category of (a) larking about (b) the clean-up operation or (c) souvenir hunting and perhaps (d) training exercises.
Moving Nevill's body and positioning his head in the coal shuttle seems likely to have been some kind of macabre stunt of extremely poor taste, I saw similar stuff during my time involving dead bodies. It's a kind of survival mechanism I guess.
Best wishes to all.