Why some navies standardized on the five-inch gun

Why did Australia and Canada move to the American five-inch gun while Britain kept the 4.5-inch gun?

Britain could sustain its own calibre, while other navies benefited from adopting the more widely supported American five-inch system.

Working with the Americans and using an available system favoured the five-inch gun. Britain retained the 4.5-inch calibre because its fleet was large enough to justify a separate standard. Australia and Canada instead went with the larger manufacturer. National pride is also offered as part of the British decision.