Prince Harry reportedly recalls Prince William's four-word response after learning Meghan Markle was pregnant in his upcoming memoir.
It was revealed that Meghan was expecting the couple's first son Archie in late 2018 - months after the couple tied the knot in Windsor several months earlier.
Now it has been reported that Harry reveals he and Meghan shared their happy news of the pregnancy at his cousin Princess Eugenie's wedding in October 2018 in his book Spare.
And the book also is said to contain what Harry says his brother William's reaction was when he was told he was going to be an uncle.
According to Hello!, the memoir says Harry broke the news to his brother during a reception in Windsor Castle.
And it is said William reacted exactly how Harry would have hoped and told him "we must tell Kate".
Meanwhile, it is reported the book claims King Charles was also delighted that he was to become a grandfather for the fourth time.
Other revelations that Harry includes in his book regarding his children are that while Meghan was in labour with Archie, he devoured a Nando's which had been brought to the hospital by his bodyguards.
Meanwhile, he also reportedly reveals how he delivered Lilibet and opens up about her first meeting with the Queen - and how during this meeting the late monarch was delighted at Archie's attempt at a royal bow.
Meghan gave birth to Archie in May 2019 at the private Portland Hospital in London the couple broke from tradition and decided not to pose for the traditional 'hospital steps' royal photos.
However Harry gave a spontaneous interview outside Windsor Castle shortly after Archie was born, praising his wife.
He said: "I'm very excited to announce that Meghan and myself had a baby boy this morning, a very healthy baby boy.
"I haven't been at many births. This is definitely my first birth - it was amazing, absolutely incredible.
"I'm so incredibly proud of my wife.
"And as every father and parent would say, your baby is absolutely amazing."
In another break from royal tradition, the couple kept details around Archie's arrival top secret. The couple confirmed Archie's arrival with a simple post on their Sussex Royal Instagram account - which said "it's a boy!"
This story is based off a translated version of Prince Harry ’s memoir Spare. Spare published by Penguin Random House will be available to buy in the UK on January 10.