Queen Elizabeths with 16.5-inch guns reshape the naval race

How would 16.5-inch guns on the original Queen Elizabeth class affect Royal Navy development?

The ships become larger and either faster with eight guns or slower with ten, while the United States jumps toward 18-inch weapons and later treaty limits rise sharply.

The British weapon under discussion was a 16.5-inch design, not a 16-inch gun. Larger barbettes would lengthen and widen the Queen Elizabeth hull, creating space for more boilers and perhaps a 28-knot eight-gun ship. Keeping the speed near 25 knots could instead support ten guns. Once Britain fields a 420 mm weapon, the United States has little reason to stop at 16 inches in a qualitative competition and may move directly toward 18-inch guns. Germany would face another costly escalation while attempting its own large-calibre response. A later arms-control settlement would probably accept 18-inch weapons and standard displacements around 45,000 to 50,000 tons because the existing ships would already be much larger.