Prince William found out that he will be king in a heartbreaking way that involved his younger brother Prince Harry.

When he was much younger, Prince Charles and Princess Diana shielded Prince William from the reality that he would one day have the most important position in the British monarchy. But when he started going to school, his classmates broke the truth to him.

In the book “William and Catherine: Their Lives, Their Wedding,” royal author Andrew Morton detailed an incident between Prince William and his schoolmates.

“The innocence of his position was soon ended by fellow pupils, who left him in no doubt who he was. On one occasion, a classmate reportedly asked him: ‘Don’t you know the Queen?’ William looked at him and replied: ‘Don’t you mean Granny?’” Morton said.

According to the royal author, Prince Harry was also one of those children that teased Prince William about his future status. During one occasion, Prince William expressed his desire to become a policeman so that he could look after his mother. Prince Harry told him that he couldn’t be one because he will become king.

Earlier this year, broadcaster Jeremy Paxman also recalled a conversation he had with Princess Diana about her sons’ future. In the documentary “Paxman on the Queen’s Children,” he said that the Princess of Wales often heard her firstborn saying that he doesn’t want to be king. Prince Harry would always reply that if his older brother didn’t want the role, he would gladly take it.

Meanwhile, Prince William’s dad, Prince Charles, also revealed how he knew that he would be king at such an early age.

“I think it just dawns on you slowly that people are interested and slowly you get the idea that you have a certain duty and responsibility,” he said.

As of late, Prince Charles and Prince William haven’t been crowned king. Queen Elizabeth II is still the reigning monarch.