The Great Unmentionable is, of course, the fact that in general less informed and less intelligent people voted for Brexit while more informed and more intelligent people voted for Remain. The culture divide is therefore similar to that in the USA where ignorant unintelligent people vote Republican and intelligent informed people either abstain or vote Democrat. As our world is increasingly complex we’re likely to see this divide (between people who can’t understand global challenges versus people who at least make an attempt) grow and grow. But as it’s not at all Politically Correct to suggest that some people are more intelligent than others and that this fact might actually matter, everyone’s going to ignore the metaphorical elephant in the room until said pachyderm wrecks the entire building.