Tillman pressure could unite Britain's capital-ship types

Would Britain keep separate battleship and battlecruiser lines when responding to Tillman III?

Perhaps not; the challenge could accelerate Britain's existing move toward fast battleships, while the exact design depends on timing.

The answer depends on when the American ship appears. A postwar challenge makes later 18-inch concepts more plausible, while a 1917-18 start points toward earlier alphabet-series studies. The pressure could accelerate Britain's existing movement toward fast battleships rather than preserve separate capital-ship branches. That shift would be evolutionary, so the exact design still turns on the timing of intelligence, orders, and available gun programs.