Rapid aircraft development outpaced naval air defence

Were navies adequately prepared for the air threat in 1941-42?

Not fully; aircraft improved exceptionally quickly, and navies needed better dual-purpose and medium anti-aircraft weapons sooner.

Aircraft engines advanced from roughly 600 horsepower to 2,000 horsepower across little more than a decade, sharply changing attack performance. The Royal Navy needed its 4.5-inch dual-purpose weapon earlier, while the US Navy benefited from the 5-inch/38 and rapidly adopted the 40 mm Bofors. Existing British 4.7-inch and 4-inch weapons addressed different bomber threats but did not provide the same all-round answer. Apparently reasonable prewar anti-aircraft arrangements became inadequate as aviation technology advanced faster than ship armament programs.