According to the 1992 biography, Diana: Her True Story, the late Princess claimed the Prince of Wales made some rather hurtful comments after Harry was born which made her extremely upset.
"Oh God, it's a boy," Diana explains of the first words spoken by Charles after welcoming their second child.
"And he's even got red hair!."
She went on to reveal that the comments made her "close off."
"I knew Harry was going to be a boy because I saw on the scan but Charles always wanted a girl," Diana told the documentary.
"He wanted two children and he wanted a girl. I knew Harry was a boy and I didn't tell him.
"Harry arrived, Harry had red hair. Harry was a boy."
Royal baby: Meghan Markle gives birth to baby boy
On May 6, 2019, Harry and his Meghan welcomed a "healthy" and "beautiful" baby boy into the world.
Surprisingly, Prince Charles is yet to comment on the arrival of his fourth grandchild.