Wiggins and Bamber weren't close. He was his mechanic. No other witness in the case realm makes any mention of Jeremy Bamber making any sort of conversation along this lines, whether it be Julie, Colin, friends or family. It almost seems JB wished to talk about it to a third party who had no particular relationship of a serious nature to him.
Even if JB is gulity, why would he be alleging police involvement as early as 85? Even before arrest?