Princess Charlotte caught the attention of the media and royal family fans on Monday as she waved to onlookers outside St. Mary’s Hospital in London. What the 2-year-old princess may not realize is that she made history the moment her younger brother, the third child of Prince William and Kate Middleton, the Duke and Duchess of Cambridge, was born.

The baby — whose name will be approved by the queen before it is announced — is the first prince not to automatically jump ahead of his older sister in the order of succession to the throne. He is fifth in line to the throne. Charlotte maintains her place as fourth in line, behind her grandfather, father, and older brother.

For hundreds of years, the rules governing the line to the British throne reflected a system of male precedence, or primogeniture. Male heirs automatically moved ahead of female siblings even if the girls were older. Queen Victoria’s first child was a daughter, Princess Victoria, born in 1840. But her second child, a son, born in 1841, immediately became her heir (and was later crowned King Edward VII).

The rules of primogeniture still applied when the queen’s own children were born. Prince Charles, the heir to the throne, was born in 1948. But his sister, Princess Anne, who was born in 1950, was bumped down the line by her younger brother Prince Andrew, when he was born in 1960, and dropped down again when Prince Edward was born in 1964.

As societal thinking about gender changed over the next few decades, the old rules looked antiquated and biased, even for an ancient hereditary system. Several European monarchies, such as Sweden and Denmark, reformed their rules of succession to apply to heirs in order of birth. In 2011, during a meeting of the heads of governments of the Commonwealth — of which Britain is a member — legislation to end gender bias in the order of succession was agreed to in principle.

(Chris Jackson/Getty)
(Chris Jackson/Getty)

The Succession to the Crown Act of 2013, which is retroactive to the date of the 2011 Commonwealth meeting, amended the relevant British statutes to make succession to the throne independent of gender. The legislation was introduced when the Duchess of Cambridge was pregnant with her first child and ensured that the baby, whether a boy or girl, would be William’s heir. The couple had a son, Prince George, in 2013 and a daughter, Princess Charlotte, in 2015.

The significance of the legislation has come up again because under the old tradition, the new baby prince of Cambridge would have otherwise moved ahead of his older sister.

Recent examples of male heirs leapfrogging their older sisters in the line of succession include James, Viscount Severn, the son of the queen’s youngest son, Prince Edward, and his wife, Sophie, the Countess of Wessex. James, who was born in 2007, is 11th in line to the throne, one place ahead of his older sister, Lady Louise, who was born in 2003.

Among the current queen’s cousins, Prince Michael of Kent, born in 1942, jumped ahead of his older sister, Princess Alexandra, who was born in 1936. (He later lost his place in line to the throne because he married a Catholic, which was not allowed under the old rules. The 2013 law change restored him in the order of succession.)

The preference for male heirs explains why when the current queen was first in line to the throne, during the reign of her father, King George VI, she was referred to as the heiress presumptive — presuming a male heir was not born and moved ahead of her. When Elizabeth became queen, her firstborn, Prince Charles, was male so he was considered her heir apparent.

Queen Elizabeth, who celebrated her 92nd birthday on Saturday, is Britain’s longest-reigning monarch but only its third reigning queen since 1707, when the Parliaments of England and Scotland passed legislation creating the United Kingdom of Great Britain.

With Prince Charles, Prince William and Prince George first, second and third in line to succeed her, Britain stands to have a series of kings in the future.

The updated law of succession, however, means that a future princess could one day be born to be queen.

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