A 1937 3-inch/70 would reshape Royal Navy air defense

Which Royal Navy ships would receive a 3-inch/70 if it were available in 1937?

Almost everything that could carry it; its rate of fire would displace many 4-inch and some pom-pom installations.

A rapid-fire 3-inch/70 available in 1937 would see extremely broad adoption. Its rate of fire would make it preferable to many twin 4-inch installations, and even Tribal-class destroyers might trade a pom-pom position for a mount if weight could be managed. A mature medium-caliber dual-purpose weapon could alter prewar anti-aircraft fits across many ship types. That change would concentrate more fleet-wide antiaircraft fire in a common high-rate weapon.