The shared logic behind Egret, Tribal, and Black Swan guns

Is there a connection between the twin-gun layouts of the Egret, Tribal, and Black Swan classes?

They reflect related thinking about balanced firepower, although the ship types and their roles were not identical.

A relationship appears in the design studies behind the classes, particularly the effort to balance gun numbers and useful firepower. The comparison does not reduce the Egret, Tribal, and Black Swan layouts to one copied arrangement, because the ships served different purposes. The comparison also includes surviving examples of the four-inch weapon as a tangible link to the system being discussed.