(d) No retained capital ships or aircraft-carriers shall be reconstructed except for the purpose of providing means of defence against air and submarine attack, and subject to the following rules: the Contracting Powers may, for that purpose, equip existing tonnage with bulge or blister or anti-air attack deck protection, providing the increase of displacement thus effected does not exceed 3,000 tons (3,048 metric tons) displacement for each ship. No alterations in side armour, in calibre, number or general type of mounting of main armament shall be permitted except: (1) in the case of France and Italy, which countries within the limits allowed for bulge may increase their armour protection and the calibre of the guns now carried on their existing capital ships so as not to exceed 16 inches (406 millimetres) and; (2) the British Empire shall be permitted to complete, in the case of the Renown, the alterations to armour that have already been commenced but temporarily suspended.