In October 2011 the British government quietly introduced a new law. This was the rule of absolute primogeniture, which meant that the first child of William and Kate would ascend to the throne regardless of gender. Though George was the first-born child, if Charlotte had been the first-born, she would have changed years of tradition by being placed ahead of her brother in the royal line.
Ever since 1066 and the Norman Conquest, Britain had used male-preference primogeniture. That meant that it was very difficult indeed for a female first-born child to ever take the throne. She would have to – like Queen Elizabeth II – have no living brothers or nephews. But Kate’s first pregnancy ended that sexist tradition.
After Prince George was born in 2013, Princess Charlotte came along two years later. Most people assumed the couple would stop after two children, especially as Prince William himself was one of only two. A health condition that Kate had, which affected her badly during pregnancy, also led people to assume there would be no more kids.