The case features two of my personal bugbears with expert testimony.
[Firstly a little background, I work in IT, have a speciality in security and digital forensics, and have testified as an expert witness.]
Primus: the "celebrity expert". This isn't common today, but there have been experts whose testimony was grossly over-valued because of who they were and the reputation they had built up. Spilsbury ("The Lethal Witness") and Simpson are examples of this; their testimony wasn't questioned, even when it was felt to be wrong, because of their reputation. People were hanged because of this over confidence in expert testimony.
James Cameron, whose far from expert opinion figured in the Chamberlain case, is a lesser example of this.
Secundus: inability to properly examine expert testimony. As you pointed out the scientific evidence was very convincing in the Chamberlain case, and it shouldn't have been. It was pretty terrible. But it wasn't challenged, it was allowed to stand and Lindy Chamberlain was jailed because of this.
In my opinion the destruction of the samples and plates used in testing denied the defense the ability to properly cross-examine the scientific evidence and should have lead to it being deemed inadmissible.
Ultimus: Barristers. A major part of his dislike of the adversarial justice system is down to barristers. This doesn't appear to have been a major factor in the Chamberlain case, though I haven't (and don't plan to) read the court transcripts.
Barristers want to win regardless of the truth; science should be about the truth.