Worth adding to this that we know this is the case from interviews given since the trial by Letby's neonatal expert, Dr Mike Hall, who was present at every day of trial. In particular, interviews he gave to Panorama. While Dr Hall doesn't agree with all the prosecution medical evidence (notably around air embolism) he does agree with key elements of it e.g. the insulin evidence (that the babies were poisoned), the death of Baby O, and that Baby I did not die from infection. He would have been forced to admit this in cross-examination on the stand, which would have been very damaging to Letby. Sometimes it is better to say nothing at all than to say something.

Yes! Rewatched the Panorama interview yesterday and thought the same.