Why the cruiser ceiling stops at 9.2-inch guns

Why would Britain not push the cruiser gun limit up to 10 inches?

Because the United States wanted the smallest possible cruiser weapon and 9.2 inches already represented the upper end of the contemporary negotiating range.

The actual debate began from existing large-light-cruiser weapons and moved only reluctantly upward. American negotiators wanted a clear capability break between cruisers and capital ships. Britain and France had to push the historical settlement from a 7.5-inch reference toward eight inches. In the alternate conference, 9.2 inches is therefore a generous compromise grounded in proposals of the period rather than an invitation to create miniature capital ships.