If we're allowed to continue this discussion!
I tend to agree with your thoughts about WSC Double Zero. Churchill was an arch-pragmatist (fortunately for us!) who had probably calculated as such. My point is though that his hand was somewhat forced as the public at large (and also parliament to a large extent) would have all-but demanded some form of retribution, having regarded the 'accident' as being a deliberate act (not knowing the truth). It is in some ways similar to the obligation felt by President Truman to use the A-bombs on Japan to shorten the war and 'save American lives' (amongst numerous other reasons including demonstrating US military might to the Soviets in the developing Cold War); US public opinion would've been outraged if they knew these bombs had existed and not used...