I do think that air embolism quotation is still relevant and reasonable, though. Because Evans consistently implies that he has excluded other causes, found something "consistent" with air embolism, and then can add non-specific findings that are not essential to the diagnosis (so the diagnosis stands if details of rashes and X-rays are challenged).
Here he is in this week's Private Eye
MD asked Dr Evans two questions: 1. What other causes of death or deterioration did you consider alongside deliberate harm? 2. How did you exclude them?
His responses were:
1. "In relation to the seven deaths, it was possible firstly to exclude natural causes such as haemorrhage, infection or some congenital problem. The unexpected collapses were very unusual -- and consistent with air embolus, air injected into the bloodstream. This was the most likely cause before the radiology evidence was flagged up by Owen Arthurs (air in the great vessels) and the peculiar skin discolouration noted by the local medics. These findings were not essential to the diagnosis but added to the clinical presentation already noted.
"Having made the diagnosis (the injection of air), it could have happened accidentally or intentionally. If it was accidental, the cause would have been easily spotted, as it's normal for two nurses (or a doctor and a nurse) to be present when babies are given fluids or drugs intravenously. Any deterioration would have occurred there and then. There were no reported events of this nature. The collapses occurred when the infants were in Letby's sole care."
1. "I was able to exclude other causes, such as the ones noted above, because there were no other causes. Sorry if that sounds rather odd. But that's clinical practice for you."
There is a lot to pick apart there, but there is no doubt he is treating air embolism as a diagnosis of exclusion, doing exactly what Lee describes.
The Court of Appeal could certainly state, accurately, that the jury did not rely only on one specific and certain factor to determine that there had been death by embolism. But they did rely on Evans's evidence, which does seem to have treated air embolism as a diagnosis of exclusion.
I find Evans's contributions particularly disturbing in this case.