Destroyer size, treaty tonnage, and deployable numbers

Why was the Royal Navy reluctant to build larger destroyers after successful large classes?

Cost, aggregate treaty tonnage, and readiness cycles encouraged more hulls of smaller size, even though growing modern mission requirements favour larger destroyers.

Larger destroyers cost more individually and, under an aggregate treaty limit, leave room for fewer hulls. Availability also depends on how many ships are deployed, preparing for sea, or in maintenance. An illustrative ten-ship force is described as keeping about four at sea and another two to four able to prepare within 24 to 72 hours. Those are planning examples rather than guaranteed readiness ratios. Larger modern multi-mission ships are still expected, with the future Type 80 series estimated here at 12,000 to 15,000 tons fully loaded. The tradeoff is between the capability of an individual ship and the number of places the fleet can cover.