Comparing British 4-inch, 4.5-inch, 4.7-inch, and 5.25-inch guns

How effective were the Royal Navy's principal 4- to 5.25-inch antiaircraft and dual-purpose guns?

The 4.5-inch was the best-balanced design, with the other calibers useful but more compromised in self-defense, handling, or surface effect.

The 4-inch gun was a capable high-angle weapon for the conditions of 1939-40. The 4.7-inch could protect other ships but was less satisfactory for close self-defense unless mounts and handling arrangements were modified. The 5.25-inch was awkwardly large for antiaircraft handling without being ideal as a surface gun. The 4.5-inch offered the strongest balance by combining useful shell effect with more practical dual-purpose handling.