The former First Lady said, "What's true among the world leaders is that there are people who handle the protocol, and usually the people they represent do not want the whole record." So you're wondering who you're doing it for because you do not want it, we do not want it. "But that's the way it is.
"So I do not know that I could have done anything else because it was a natural human reaction.
Ms Obama then explained her views on the social conventions that govern the meetings of world leaders.
She said, "Over the course of my time on the international stage, I've learned that I've either held my hands together or been behind my back to make sure I think before I react naturally.
"But at that moment, no.
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"That was absolutely right, because it was human."
In her new autobiography, "Becoming," Ms. Obama said, "We were informed in advance of the protocol: we would formally greet the Royals before boarding their vehicle to make the short drive.
"I would sit in the front next to the ninety-four-year-old Prince Philip, who would drive, and Barack would sit in the back seat next to the queen."
The former First Lady went on to explain how the queen subverted the royal record in a rare act of disobedience.
She said, "After settling down in a field on the castle grounds, we said to our hell the queen abruptly put everything in motion and signaled me to sit in the back seat of the Range Rover.
"I froze, trying to remember if anyone had prepared me for this scenario, whether it was more polite to join in, or insist that Barack take his rightful place by his side.
"The queen immediately took up my concerns and had none of it.
"Did they give you a rule about that?" She said, dismissing all the excitement with a wave of her hand.