Chris Scott
The problem we all have is that we do not have access to the FDR/QAR. And the AAIB is not telling us if thrust above idle was used at any time during the descent. All they have said is that "the A/C entered the hold at Lambourne at FL110; it remained in the hold for approximately 5 minutes, during which time it descended to FL90."
To sum up: we don't know.
Good post Chris.
But there is some room for some presumption
If the missing info (FDR/QAR .... etc.) was to have confirmed any speculations along these lines then surely the AAIB/Boeing would have acted on it by now in a heads up to the operators.
back to reading between the lines