A delayed war could produce British 9.2-inch heavy cruisers

Could Britain build further improved Town-class cruisers if the war started later?

Yes, but the end of treaty limits might instead push the Royal Navy toward purpose-built 9.2-inch heavy cruisers.

Improved Town-class cruisers are plausible, although a delayed war and failing treaty system could open a heavier path. British designers could move to cruisers armed with 9.2-inch guns once treaty restraints no longer fixed the familiar categories. Japan planned to convert some nominal light cruisers to heavier armament, but those older hulls would compare poorly with a purpose-built British heavy cruiser. The result would be another round of competitive escalation instead of a simple continuation of the 6-inch cruiser line. Treaty timing directly affects gun caliber and hull design.