Why Nelson and Rodney look so unusual

Why were Nelson and Rodney so distinctive in design?

They were new 1920s battleships built from First World War experience while constrained by treaty limits, British infrastructure, and limited government spending.

The answer treats the Nelson class as a concentrated expression of First World War lessons within the limits imposed in the 1920s. Treaty displacement, existing British industrial capacity, and the government's Ten Year Rule all narrowed the available choices. Other navies studied comparable arrangements. The Royal Navy had a particular reason to implement one immediately, and the ships' unusual appearance records those constraints in their layout.