The Dallying Duke of Marlborough

This historical corner of the Web is exercised over the misquotes and tall tales about Winston Churchill that clutter the Internet—by everybody from Washington quarterback Robert Griffin III to assorted authors and politicians (see “Churchillian Drift”).
They range from RG III’s recent “Courage is what it takes to stand up and speak” (nobody knows who said that, but Churchill didn’t) to the fiction that Alexander Fleming twice saved Churchill’s life.
But here’s an amusing example of Churchill himself destroying a Churchill myth—about his ancestor John Churchill, First Duke of Marlborough. Reference is to the early pages of Marlborough: His Life and Times, vol. 1:

At the beginning of 1671 John Churchill was enjoying the company of Barbara, First Duchess of Cleveland. She was twenty-nine, he twenty. Winston Churchill writes:
Affections, affinities, and attractions were combined. Desire walked with opportunity, and neither was denied. John almost immediately became her lover, and for more than three years this wanton and joyous couple shared pleasures and hazards…not severed until the dawn of his love for Sarah Jennings [later his Duchess] in 1675.
Unfortunately or fortunately (we report, you decide), the lovely Barbara had also excited the passions of King Charles II, the product of which were several of Barbara’s children. Churchill continues:
Two of the adventures of the lovers are well known. The first [is] that, being surprised by Charles in the Duchess’s bedroom, John saved her honour—or what remained of it—by jumping from the window, a considerable height, into the courtyard below. For this feat, delighted at his daring and address, she presented him with £5000.
The second anecdote is attributed to the French Ambassador, Barillon. The Duke of Buckingham, he says, gave a hundred guineas to one of his waiting-women to be well informed of the intrigue. He knew that Churchill would be one evening at a certain hour in Barbara’s apartments. He brought the King to the spot. The lover was hidden in the Duchess’s cupboard (she was not Duchess till 1670). After having prowled about the chamber the King, much upset, asked for sweets and liqueurs. His mistress declared that the key of the cupboard was lost. The King replied that he would break down the door. On this she opened the door, and fell on her knees on one side while Churchill, discovered, knelt on the other. The King; said to Churchill, “Go; you are a rascal, but I forgive you because you do it to get your bread.”
Now Winston Churchill loved a good fable as well as the next fellow. When his literary collaborator Bill Deakin challenged a well-known myth in his History of the English-Speaking Peoples, Churchill declared: “At times of crisis, myths have their historical importance.” But he was having no nonsense about his ancestor John Churchill:
It is a good story, and the double-barrelled insult is very characteristic of Charles. But is it true? Barillon, who did not himself arrive in England till September 1677, probably got it from his predecessor, Courtin. He fixes the date as 1667….Here is a fine exposure of these gossips. There can be little doubt, as we have shown, that nothing of this kind can have occurred before 1671. It is therefore one of those good stories invented long afterwards and fastened, as so many are, on well-known figures.
We have dwelt herein on falsehoods known as Churchillian Drift. File this one under Marlborough Drift.
Churchill was nevertheless under no illusions about the faults of his ancestor. “What a downy bird he was,” he wrote his wife in 1935…
He will always stoop to conquer. His long apprenticeship as a courtier had taught him to bow and scrape and to put up with the second or third best if he could get no better. He had far less pride than the average man.