You know how Archie and Lilibet Sussex didn't become Prince and Princess until their grandfather was monarch, rather than their great-grandmother?
Well, apparently, their cousins the Wales children could have followed the same path if said great-grandmother—the late Queen Elizabeth II—hadn't decided otherwise.
According to the Mirror, King George V introduced a rule in 1917 that determined that only certain royal descendants were entitled to Prince and Princess titles at birth: all of the monarch's own children, plus grandchildren born through the male line.
By this logic, Prince George, Princess Charlotte and Prince Louis would have been too far down the line of succession to be entitled to their princely titles from birth, and would only have been granted these once Elizabeth passed away.
Presumably because he was destined to be a future monarch, the late Queen decided that George, now 9, would be known as Prince George from the get-go, and ended up changing the rule so that his younger siblings Charlotte, now 8, and Louis, now 5, were also granted Princess and Prince titles respectively.
As for Archie, 4, and Lili, 2, it was widely reported that they were entitled to use Prince and Princess titles should their parents wish from the moment their grandpa King Charles acceded to the throne, but it wasn't until after Lilibet's christening that a spokesperson referred to the little girl as "Princess Lilibet."
Shortly afterwards, the change was concretized with an update to the official royal line of succession website reflecting the children's new titles.
As it stands, George is second in line to the throne, Charlotte is third, Louis is fourth, Archie is sixth, and Lilibet is seventh.
