Would 16.5-inch battleships still appear after an 18-inch Agincourt?

Would the Royal Navy still build 16.5-inch-gunned battleships after moving directly to an 18-inch Agincourt?

Possibly. An unsatisfactory 18-inch rate of fire could prompt experiments with a 16.5-inch weapon.

Jumping to an 18-inch gun does not guarantee that every later design keeps it. A 16.5-inch experiment remains possible if service experience shows that the larger weapon cannot deliver an adequate rate of fire.