Why Britain designed the Lion-class battleships

Which foreign battleships were the Lion-class designs meant to counter?

They were primarily Britain's own 16-inch-gun response to a broad international trend, not a counter to one specific class.

The design belongs to a general caliber shift rather than a one-for-one response to a named foreign class. Other navies were moving toward 16-inch weapons, so Britain wanted its own battleship built around that standard. The requirement was comparative and institutional even when no single opponent was laying down the exact ship the Lions were meant to defeat. Retaining 15-inch guns might also have simplified construction enough to bring the class into service.