Back in 2009, Michelle Obama threw out the royal protocol handbook and dared to hug the Queen, sending newspapers and commentators into a spin as they tried to work out why the then-First Lady would do such a thing.

Finally, nearly 10 years later, Michelle revealed the true reason for the affection moment with the monarch, explaining that they had just bonded over having sore feet.

The two women were at a G20 summit, and writing in her new memoir ‘Becoming’, Obama explains that the Queen had commented on how tall she was, before asking if her shoes were painful.

“She shook her head,” Obama writes. “‘These shoes are unpleasant, are they not?’ she said. She gestured with some frustration at her own black pumps.

“I confessed then to the Queen that my feet were hurting. She confessed that hers hurt, too.

“We looked at each other then with identical expressions, like, when is all this standing around with world leaders going to finally wrap up? And with this, she busted out with a fully charming laugh.”

Obama “then did what’s instinctive to me any time I feel connected to a new person, which is to express my feelings outwardly”.  

“I laid a hand affectionately across her shoulder,” she writes. “I couldn’t have known it in the moment, but I was committing what would be deemed an epic faux pas.”

‘Becoming’ includes a number of other personal and professional revelations from Michelle Obama, who writes about her career as a lawyer, her marriage to Barack, and her time in the White House.

In particular, she’s been praised for discussing marriage counselling and using IVF to conceive her two daughters after having a miscarriage.