And while it is not known what Her Majesty said during the intimate meeting, a newly resurfaced report reveals the crude joke the monarch made after the birth of Prince William.
According to a 2014 Daily Express report by royal correspondent Camilla Tominey, new father Prince Charles sent a gushing letter to his second cousin Patricia Mountbatten, announcing the happy news that Prince William had been born.
"The arrival of our small son has been an astonishing experience and one that has meant more to me than I ever could have imagined,” Charles is quoted as saying.
"I am so thankful I was beside Diana's bedside the whole time because I felt as though I'd shared deeply in the process of birth and as a result was rewarded by seeing a small creature who belonged to us even though he seemed to belong to everyone else as well."
However, Ms Tominey claimed the Queen reacted in a very different way to her grandson's birth.
"Thank goodness he hasn't ears like his father,” she is said to have quipped upon meeting William.