British First World War designs judged mistaken

Which British First World War ship designs were mistakes?

The Courageous-class large light cruisers as built and the Admiral class as originally conceived are the clearest examples.

Courageous, Glorious, and Furious are singled out as built, along with the Admiral class as first conceived. Those qualifiers keep the judgment tied to the original designs rather than every later use or redesign of the ships. Resistance, the unbuilt third Renown-class battlecruiser, is the preferred alternative. A following ship reference is indistinct and does not support another firm identification.