I don't think LL is innocent, my debate is about whether the evidence was guilty beyond reasonable doubt given the evidence, and the returned not-guilty and majority verdicts on most charges show that it was not absolutely overwhelming. I do wish CCTV had been installed (not everywhere on neonatal wards but where there is a statistical pattern of too many deaths) because relying on statistics and hoards of handwritten notes is not utterly beyond doubt convincing and now there will be room for appeal, but mainly because it might have stopped her killing more babies, although she's so arrogant (I mean even if she wasn't a killer, making a complaint and taking your dad along to challenge 7 consultants when there were unexplained deaths and your conduct wasn't A1) that she probably would have continued.
There is no useful DNA evidence here, no witness that saw something incontrovertibly bad (the one witness that did saw he standing with a baby desaturating and her not doing anything which is explicable), no video of her collecting the insulin. It IS hard to get convictions on that basis not because she's innocent (I don't think she is) but because the evidence is just not as compelling as it might be, similar cases have fallen or been overturned later on statistics for example (such as the Sally Clark case). In the Ben Field case I mentioned earlier they almost didn't get a conviction out of even worse circumstantial evidence (diaries of hate, plans, DNA on glass), and it was only some detective showing that a statement made by him could not have been true that eventually clinched it.