This is ahistorical to a fault: the UK introduced postwar social reforms that were already present in continental European nations. Britain's industrial decline can be traced to long before the Marshall Plan, and even the war: it's tied inextricably to the UK's "colonial prestige" politics, including the desire to run a massive and expensive empire long after its extractive value had been maximized.

> Have any communist countries achieved such success? Any socialist ones?

I don't know why you're fixated on this. Again: nobody in this thread has made this claim. The only thing under discussion is whether it's reasonable to naively treat postwar Europe's recovery as a triumph of capitalism, which it isn't.