County-class cruisers provide the example of ships prepared to receive 4-inch armour plates held ashore. The proposed extension is a battleship with an 8-inch peacetime belt and heavier 13-, 14-, or 15-inch plates ready for war. Its hull would need the displacement capacity and internal subdivision for that heavier condition from the outset. The risk is accepting reduced protection while relying on sufficient warning to fit the armour. Outright understatement is another possibility because a 35,000-ton ship and a 36,000-ton ship would be difficult to distinguish by appearance. Declared intentions could also change with a successor in command.
Notable Point · 6:41-9:37
Light peacetime armour on a hull prepared for war
A lightly armoured peacetime ship could retain the subdivision and weight capacity needed for a much heavier wartime belt.