A 12-inch/50 path carries longer guns into later British calibres

How would British heavy-gun development change if its 12-inch ships successfully used 50-calibre weapons?

Britain would probably continue 50-calibre development into its later 13.5- and 15-inch guns while retaining built-up construction.

The counterfactual begins with British 12-inch ships using 50-calibre guns. The navy would likely continue favoring longer barrels as it moved into larger calibres, alongside continued use of built-up gun construction. The likely result is a family of longer 13.5-inch and 15-inch weapons rather than a return to markedly shorter heavy guns, although the exact intermediate calibre remains less certain.