To my knowledge the aft deck of the Counties are one and half lower then the Helideck. Also Fuller how many sketches did you seen about the hulls?
I've based mine entirely on the Counties
The only sketches I have looked at are the ones in
at this link and the the sketches of a Batch II county class in Friedman's British Destroyers and Frigates. I agree, the quarter deck on the actually built County class is a deck and a bit above the waterline. On the sketches of the NIGS ships it is two full decks above the waterline.