Why the Royal Navy did not adopt a 50-caliber 15-inch gun

Why did the Royal Navy not develop a 50-caliber 15-inch gun for its new battleships?

The decision to arm the King George V class with 14-inch guns removed the immediate requirement, although a triple-turret 15-inch alternative was technically attractive.

The decision to arm the King George V class with 14-inch weapons removed the immediate programmatic reason to develop a new long 15-inch gun. The larger caliber is preferred here, with three triple 15-inch turrets presented as a more effective alternative to the historical ten-gun battery. Nelson and Rodney already provided experience with triple mountings, reducing some of the design novelty. A 15-inch weapon adapted to their larger barbettes might also permit greater elevation and range while creating a common modernization path for older battleships.