The Duke and Duchess of Cambridge's daughter Princess Charlotte made history when she was just two years old after the birth of her younger brother, Prince Louis, in April 2018.
Charlotte became the first female royal to benefit from The Succession to the Crown Act (2013), which states that girls will not be overtaken by younger brothers.
While Charlotte has retained her place as fourth-in-line to the throne in front of Louis, other female royals missed out on the change, as the Act only applies to those born after 28 October 2011.
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The Queen and the Duke of Edinburgh's only daughter Princess Anne is much further down the line of succession than her younger brothers Prince Andrew and Prince Edward. The Princess Royal, who celebrated her 70th birthday in August, is currently in 14th place behind her niece Lady Louise Windsor.
If the rules had been changed at the time of Anne's birth in 1950, her children Peter Phillips and Zara Tindall would be much closer to the throne than their cousins Princess Beatrice and Princess Eugenie, who are currently ninth and tenth.
The Earl and Countess of Wessex's daughter Lady Louise Windsor, 16, was also overtaken by her younger brother James, Viscount Severn in the line of succession after his birth in 2007. James is currently 12th in line, while Lady Louise is 13th.
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Charlotte kept her place in the line of succession when Louis was born
Princess Charlotte is the only female royal who has benefited from this change so far, but if Princess Eugenie gives birth to a daughter in early 2021 and her next child is a son, she would be the next.
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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