Answer supplied by veteran US presidential speechwriter Ted Sorensen in the New York Times:
"Speaking from the heart to the heart, directly, not too complicated, relatively brief sentences, words that are clear to everyone."
He cites as an example Churchill's opening line when announcing to the country the fall of France:
"The news from France is very bad."
Almost comic on first reading, the line later resonates with the essence of good communication: clarity and authenticity.
Question: could the same bad news ever be delivered unvarnished today?