Royal Navy ships in 1939 consistently carried heavier anti-aircraft armament than comparable foreign warships. This was their starting position at the outbreak of war. By about 1941, other navies had watched what British ships were facing and wanted more AA of their own.
Notable Point · 4:24:31-4:24:54
The Royal Navy's comparative AA armament in 1939
Royal Navy warships entered the Second World War with unusually heavy anti-aircraft batteries, before combat experience pushed other navies toward similar additions.