Why were there so many Lord Nelson-class semi-dreadnought designs?
Short answerThey were transitional studies exploring different heavy-gun arrangements while the Navy moved toward the all-big-gun Dreadnought concept.
NotesThe Lord Nelson studies explored several arrangements while British battleship design moved toward an all-big-gun armament. Some versions considered 12-inch guns for both main and secondary batteries, using longer guns for the main battery and shorter guns for the secondary battery. That differed from combining 12-inch and 9.2-inch weapons. The studies illustrate the competing solutions considered before the Dreadnought concept settled the immediate direction of development.