Princess Diana could do no wrong in Queen Elizabeth II’s eyes after she gave birth to Prince William.

In the book “Making of a Royal Romance,” author Katie Nicholl revealed that the late Princess of Wales and the Queen didn’t always see eye to eye. But when she gave birth to Her Majesty’s first grandchild, everything changed.

Princess Diana was able to produce a healthy heir to the House of Windsor, and it was Prince William. The Duke of Cambridge is second in line to the throne and next to his dad Prince Charles.

However, Prince William’s birth followed by Prince Harry’s arrival didn’t do Princess Diana and Prince Charles’ marriage any good. In the documentary “Princes of the Palace,” royal correspondent Ingrid Seward revealed that Princess Diana regularly reached out to the Queen for advice on what to do with her failing marriage.

Seward said that nobody is allowed to see Her Majesty without an appointment, but Princess Diana waited until her last visitor had left so she could talk to her.

“Then she’d dash in before the next one and just cry. She’d say, ‘everybody hates me, I hate my sister, I hate my mother, I hate my husband,’” Seward said.

Meanwhile, the late Princess Diana also made headlines this week after it was reported that she snubbed royal protocol with Prince William’s birth. Nicholl said in the 2011 documentary that the Princess of Wales wrote royal history when she decided to give birth at St. Mary’s Hospital’s Lindo Wing and not at Buckingham Palace.

Prince William was the first royal baby to be delivered in a hospital. Prince Charles was born in the Belgian Suit at Buckingham Palace. Princess Diana didn’t follow the royal tradition of giving birth at home because she suffered extreme morning sickness and endured a difficult pregnancy altogether.

Following Prince William’s birth at the hospital, the other royals that came after him were also born at St. Mary’s Hospital. Prince Harry, Prince George, Princess Charlotte, and Prince Louis were all born there. Prince Harry and Meghan Markle’s baby is also expected to be delivered in the same facility.

Princess Diana, Queen Elizabeth II
Pictured: Princess Diana, the Queen at the Braemer Highland games. Getty Images/PA/AFP