Sixteen-inch battleships preserve visible parity

Would Britain arm all its new capital ships with 15-inch guns?

No. The battleships would retain 16-inch guns for parity, while the battlecruiser could use 15-inch/50 weapons.

The proposed battleships retain 16-inch guns, while a new battlecruiser could use 15-inch/50 weapons. Britain would want battleships armed with the largest caliber permitted by the treaty. The practical difference between the proposed guns might be marginal at this level. Visible equality with foreign 16-inch battleships still carried political weight.