The Town class marks a shift in British cruiser thinking away from treating the treaty maximum gun caliber as automatically best. At long range, the Royal Navy expected gunfire mainly to degrade sensors, communications, and command positions rather than sink an enemy outright. Decisive destruction would require closing to roughly 18,000 yards. At that range, twelve well-designed six-inch guns could deliver enough shells quickly enough to outweigh much of the eight-inch gun's theoretical advantage.
Chapter · 2:34-5:12
Why the Town class favored twelve six-inch guns
Royal Navy fighting-range assumptions made rapid six-inch fire more useful than the heavier individual punch of an eight-inch cruiser shell.