sorry to continue the drift but, I am still looking for a rationale answer to the question: "what added safety provides to initiate the after start checklist only after the clear signal from the ground crew instead of doing the after start checklist, wait for the clear signal and then ask for taxi clearance? "
I mean, is it so difficult to give an easy explanation? I know plenty of airlines (none of them brits, but that is another matter entirely) that do and off course writes in FCOM and OM B exactly the latest and works like a charm.
it's interesting that nobody seems to be patient enough to bring forward a simple explanation on this specific point.