After the resolution of the Revolutionary War, John Adams and (later) Thomas Jefferson were diplomatic agents in London. John Adams had been there a while and had previously met the King, apparently amiably.
I happen to be reading American Sphinx by Joseph Ellis, where on page 75 it is stated:
When Jefferson visited Adams in England in the spring of 1786, the two former revolutionaries were presented at court and George III ostentatiously turned his back on the both. Neither man ever forgot the insult or the friend standing next to him when it happened.
I recently read John Adams by David McCullough where the same incident is stated differently (on page 355):
When Adams presented Jefferson at the King's levee at St. James's on March 15, George III could not have been "more ungracious" in his "notice of Mr. Adams and myself," according to an account later provided by Jefferson. Later still a grandson of Adams's would take this to mean the King had turned his back on them, and the story would become rooted in history. But almost certainly no such incident occurred. Jefferson said nothing to the effect at the time. Nor did any of the numerous ministers, courtiers, members of Parliament, and other diplomats present who were ever watchful for the slightest sign of royal disapproval or anything the least out of the ordinary. Nothing untoward was reported or hinted at in the newspapers, and importantly, nothing was ever said or written by James Adams, who, of all men, would have been enraged by any disrespect shown a minister of the United States being presented under his sponsorship.
Ellis footnotes the version he reports rather extensively, including a letter from Adams to Jefferson not too long after the event and in their respective autobiographies.
So, any further insight on what happened? Did it actually happen? Did King George III turn his back on John Adams and Thomas Jefferson?