So according to the prosecution they didn't tell the defence about the existence of two silencers, which kind of refutes your original statement? and this was not until 2020? I think that you have to concede that there is no accuracy in what you said, "the prosecution barristers told the defence barristers about the existence of a second sound moderator". I'm only asking because I'm not aware of any time when the prosecution has admitted there was a second silencer.
Let me rephrase on this point: in 2020 at Bamber's (second) Judicial Review application against the Crown Prosecution Service (seeking access to original documents as they only had copies), the defence alleged that they had been told by the prosecution at the 2002 appeal that there were two silencers.
Effectively, Bamber's lawyers were claiming in 2020 that the prosecution had taken "truth serum" and blabbed to the defence (in 2002) about there being two silencers.
I think we both agree this didn't happen.
P.S. the 2020 judgment is worth reading in full, I guess you have probably already read it.