Well, IF they do, it further raises the question of how did a 999 call from Nevill become lost -within minutes- on the very night the call is alleged to have been made. JB wasn't a suspect. They hadn't even seen the crime scene. Mick has suggested that, between them, West and Bonnet decided to lose it in case it was decided to prosecute JB later. Why would they? The two people probably furthest down the pecking order were hardly the ones to take such a momentous decision. I find that idea preposterous.
Nothing was lost, it was mishandled. A complete lack of communication and sheer confusion between officers after receiving two calls from the same name of Bamber ( two different people ) separate households. Oh the confusion

If the night in question had been a particularly quiet one before the calls, then there'd have been a mad scramble to begin working.Then came the excuses about the clock being 10 minutes fast-----no it wasn't ( when asked at trial ) it was usually right, to the minute as was the final decision.