Forty County-class cruisers and the treaty system

How would history change if Britain built its desired forty County-class cruisers alongside large postwar capital ships?

The 1930 cruiser treaty would change, and Japan might have to choose between the Yamatos and enough cruisers to match Anglo-American strength.

The counterfactual begins with a much denser British cruiser force and therefore a different negotiating baseline. The United States might respond with additional construction rather than accept such a disparity. Japan would then have to allocate limited resources between Yamato-class battleships and the larger cruiser fleet needed to answer Anglo-American numbers. Force structure before a conference can shape the treaty rules and building programs that follow.