County-class cruisers were designed to receive armor later

The ships sat conspicuously high in the water because their hulls anticipated additional belt protection that was not installed at completion. Armor could remain ashore until a later refit, keeping declared treaty displacement down while preserving a path to the intended wartime configuration. The Plimsoll or load line made the reserve visible: a cruiser riding far above it plainly had room to accept substantial weight before approaching its safe load. Foreign observers could therefore infer the fitted-for-but-not-with strategy from photographs and harbor visits even without access to British plans.