The treaty defined light surface vessels as warships outside the capital-ship, carrier, minor-war-vessel, and auxiliary categories, with displacement between 100 and 10,000 tons and guns no larger than 8 inches. It then separated vessels with guns above 6.1 inches, larger 6-inch ships, and vessels at or below 3,000 tons. New category-B cruisers above 8,000 tons were barred until 1943, though a national-security notification could reopen construction up to 10,000 tons. Any signatory invoking that exception allowed the others to exercise the same right. The 8,000-ton restriction directly explains why the Royal Navy had to seek Town-class firepower and endurance in the more constrained Crown Colony hull.
Chapter · 24:19-26:52
The 8,000-ton ceiling reshaped light cruiser design
Treaty categories separated cruisers by gun calibre and displacement, then barred new category-B cruisers above 8,000 tons until 1943 unless an escalator clause was invoked.