Why Britain retained familiar steam machinery

Why did the King George V class not adopt American-style high-pressure steam?

Because the industrial and training infrastructure was already committed to a different system, making transition costly and risky.

Britain's existing boilers, factories, and trained workforce formed a functioning production ecosystem. High-pressure steam promised advantages, but changing pressure standards also changed the equipment, maintenance knowledge, and training system around the plant. Choosing a superior but unfamiliar system during rearmament meant disrupting output and accepting early reliability risk. An optimized familiar design therefore offered lower mobilization risk even if it was not the best machinery in isolation.