If I remember the discussion on the old Warships Projects site, these ships with 220mm guns were intended to outrange the US 8in cruisers, but were abandoned when it was realised that at the ranges contemplated, the magazines would be empty before enough hits were likely to be scored.
Looking at the Pr.82, that design had a very similar staggered superstructure block too but in some depictions had a sloping wall just ahead of the fore funnel. I suspect the reason why Pr.66 and Pr.82 had such odd superstructure blocks was the simple fact that the hull was congested with the forward boiler rooms and superfiring secondary mounts not allowing enough space topside to squeeze in the size of block required for the bridge spaces and FC directors. I think the designers were attempting too much on these hulls.
_________________ Hood's Worklist
English Electric Canberra FD
Interwar RN Capital Ships
Never-Were British Aircraft