The decision Princess Diana made about William's birth that "wrote royal history".

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On June 21 1982, Princess Diana gave birth to Prince William.

It was in a hospital.

While this doesn’t seem like a major detail, it was actually very controversial.

According to Katie Nicholl’s 2011 book The Making of a Royal Romance, Diana’s decision to give birth to William in a hospital, rather than Buckingham Palace, “wrote royal history”.

While childbirth in the private Lindo Wing of St Mary’s Hospital is commonplace for the British royal family in 2018, previous to Diana it was tradition to give birth within Buckingham palace.

“Like generations of royals before him, his father Prince Charles had been delivered in the Belgian Suit at Buckingham Palace, but Diana, as the royal family quickly discovered wanted to do things differently,” she wrote.

Nicholl added that Diana had a difficult pregnancy, and suffered from morning sickness.

While Kate Middleton picked up the tradition, giving birth to George, Charlotte and Louis in the Lindo Wing, according to Vanity Fair, there is speculation that Meghan Markle might give birth at home.

Of course, giving birth in a hospital wasn’t the only royal birth tradition that Diana had to consider.  There are many.

The Queen must be the first to know about the birth, the town crier will announce the birth to the public, and there will be… canons.

41 rounds would be fired by the King’s Troop Royal Horse Artillery in Green Park, and 62 rounds of gunfire would also go off at the Tower of London following the birth of a royal.

We can’t keep up.