Could a fast Agincourt have displaced the battlecruiser?

Could a 28-knot Agincourt with six 18-inch guns have pushed the Royal Navy toward a fast battleship fleet?

Possibly. A fast Queen Elizabeth-type capital ship could have reduced the need for a distinct battlecruiser category while giving the battle fleet the mobility to concentrate across the empire.

The scenario gives Agincourt 28 knots and six 18-inch guns as a development of the Queen Elizabeth type. Such a ship could have encouraged the Royal Navy to adopt an entirely fast battle fleet and prevented battlecruisers from becoming such an enduring separate category. Speed would help capital ships move between imperial theaters and concentrate at a decisive point. They would still need armor sufficient to fight wherever they arrived. Some reduction in protection against a slower battleship could be acceptable if greater mobility produced a local numerical advantage.