Why the Admiral class stayed with 15-inch guns

Why were the Admiral-class preliminary designs with multiple 18-inch guns rejected?

They added technical, political, and construction risk while providing more gun than the intended wartime battlecruiser role required.

Britain had only recently standardized the 15-inch gun, while Germany showed no immediate move beyond the same caliber. Wartime priorities favored ships that could be justified politically and completed quickly with proven weapons. Surviving hints about problems manufacturing 18-inch guns may also have mattered, though claims of a purely technical cancellation remain uncertain. Most importantly, an 18-inch battery was excessive for a commerce-raiding battlecruiser and made more sense on a true fast battleship or a one-word battlecruiser intended to fight enemy capital ships.