What 13,500-ton treaty cruisers might have changed

How might navies use a 13,500-ton heavy-cruiser allowance under a revised London treaty?

They could build much more capable twelve-gun heavy cruisers, but the outcome would depend on national design choices and rival responses.

A 13,500-ton standard limit would open several competing design paths rather than produce one obvious cruiser. A Nelson-style concentration of the main battery could yield a compact, efficient ship, while a conventional layout would surrender some of that advantage. Twelve eight-inch guns would also narrow the volume-of-fire advantage of contemporary twelve-gun light cruisers. The strategic result would depend on which navy moved first and how rivals answered.