Future Royal Navy guns without a 76 mm option

Which guns should future Royal Navy ships carry if the OTO Melara 76 mm is excluded?

The preference is to retain 40 mm and 57 mm weapons, spread the 57 mm more widely, and explore a larger gun around six inches or 155 mm.

The preferred combination retains 40 mm and 57 mm weapons. A six-inch-class naval gun is the preferred larger addition. A remembered OTO Melara and BAE proposal is discussed with uncertainty over its exact calibre and barrel length. Interest in that proposal is a personal procurement preference, not evidence that a specific project is proceeding.