Princess Charlotte made history when she was just two years old after the birth of her brother, Prince Louis, in April 2018. Prince William and Kate's daughter became the first female royal to benefit from the change of succession law, which states that girls will not be overtaken by any future younger brothers. This meant that Charlotte retained her place as fourth-in-line to the throne, while Louis is fifth.
WATCH: Charlotte and George meet their new brother Louis at the Lindo Wing
It marked the first time that a girl has kept her rank rather than drop a place to her younger brother. The UK succession laws were updated ahead of Prince George's birth in 2013 to allow a possible firstborn daughter of Prince William and Kate to take precedence over any younger brothers.
Princess Charlotte arriving at the Lindo Wing in 2018
The decision was unanimously approved at a Commonwealth summit in Australia back in 2011, changing a 300-year rule. The old succession laws stated that the heir to the throne would be the firstborn son of the King or Queen, and the title would only pass to a daughter when there are no sons.
The Cambridges in April 2020
Speaking about the law change at the time, former Prime Minister David Cameron said: "Put simply, if the Duke and Duchess of Cambridge were to have a little girl, that girl would one day be our Queen. The idea that a younger son should become monarch instead of an elder daughter simply because he is a man, or that a future monarch can marry someone of any faith except a Catholic – this way of thinking is at odds with the modern countries that we have become."
Other monarchies in which the eldest child is the heir, regardless of gender, include Sweden, the Netherlands, Norway and Belgium, while in Spain and Monaco, males take precedence over females. For example, Prince Albert of Monaco and Princess Charlene's son Prince Jacques is the heir apparent, despite being two minutes younger than his twin sister, Princess Gabriella.
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