I think even if these ships had been built, the diesel engine would likely not have worked out. 6,000shp was a lot for the state of engine development at that time, reading D.K. Brown the submarine fleet had problems because the planned engines were not ready, though Vickers seems to have gotten its act together and most subs had Vickers diesels.
_________________ Hood's Worklist
English Electric Canberra FD
Interwar RN Capital Ships
Super-Darings
Never-Were British Aircraft