Perhaps the cops introduced this composite witness statement because they knew that the relatives had got a second silencer / sound moderator/ suppressor (DRB/1) they were going to be handing over to police, which in fact came to fruition on the 11th September 1985, when Ann Eaton gave DC Oakey that second one (DRB/1)?
We only found out about the find of the silencer / sound moderator / suppressor (SBJ/1, SJ/1, DB/1) because material from the original investigation (SC/688/85) was released to Jeremy by mistake. Perhaps whoever created the composite witness statement never anticipated that anyone would ever get to know about what had been going on involving the first silencer, how cops took possession of it, gave it back, and were handed it back and not really knowing what to do with it once they got it back because the cops were content to keep dealing with the case on the footing that what they had been dealing with was four murders and a suicide?
Some bright spark must have thought that by introducing the contents of the Jones Composite witness statement in question, that it would serve the purpose and allow for the introduction of a second silencer / sound moderator / suppressor (DRB/1) that cops anticipated they might be receiving from the relatives sooner, rather than later...
The only problem with the way cops and relatives went about trying to carry off the deception was that the lab' ended up with two Parker Hales which the relatives had handed to police a month or so apart - somebody dropped a huge clanger, since between the cops and the lab' as of the 11th September 1985, there existed two silencers / sound moderators / suppressors (SBJ/1, SJ/1, DB/1 and DRB/1), and only one proposed murder weapon, the .22 semi-automatic Anshuzt rifle owned by Neville Bamber which was not capable of having two Parker Hales attached to the end of its barrel at one and the same time...