Lady Louise has to follow strict royal rule because of younger brother James

Louise is further down in the line of succession to the British throne than James (Image: Getty)

Despite being four years older than her younger brother, Lady Louise Windsor is further down in the line of succession to the British throne because of an old and traditional law.

The daughter of Prince Edward and Sophie, the Duchess of Edinburgh, is currently 16th in line to the throne, whereas James, Earl of Wessex is above her, in 15th place.

This is because at the time of Louise's birth, the 'Succession to the Crown Act (2013)' had not come into effect - which would remove the rule that a younger son can displace an elder daughter in the line of succession.

With the new law, the order of succession is based on the order of birth, regardless of gender - and the law was introduced in 2013.

The changes were meant to reflect more modern attitudes towards gender equality, but this did not stop the rumours from swirling.

The Succession to the Crown Act was only introduced in 2013 (Image: Getty)

The Succession to the Crown Act was introduced just three months before the Princess of Wales gave birth to Prince George.

Rumours emerged that Kate may have been expecting a girl during her first pregnancy because the law was changed just months before she gave birth and therefore it would have protected her first-born's place in the line of succession - if she had given birth to a girl.

The law affected royal babies born after October 28, 2011, and therefore Princess Charlotte, who was born in May 2015 was not overtaken by her younger brother, Prince Louis, born on April 2018.

Similarly, Zara Tindall and Mike Tindall's daughters - Mia and Lena, were not overtaken in the order of succession by their younger brother, Luca.

Because of the ruling, Charlotte is not overtaken by her younger brother (Image: Getty)

The 20-year-old royal, Lady Louise, is currently in her second year, studying English Literature at the University of St Andrews in Scotland - where the heir to the throne enrolled and met his future wife, Princess Kate.

Despite Lady Louise's popularity among the public, an ex-BBC royal correspondent has claimed instead of becoming a full-time working royal  Louise may "follow a similar course" to her cousin, Zara Tindall. Jennie Bond told OK! Magazine: "She undoubtedly casts an eye at her cousin, Zara Tindall, and sees the independence and freedom and fun she has in her life."

Lady Louise Windsor, 20, is the youngest niece of King Charles, the eldest child of the Duke and Duchess of Edinburgh, and sister to James, Earl of Wessex, aged 16.

Prince Edward and Duchess Sophie's children were not given royal titles at birth after their parents decided against it. Lady Louise even turned down the royal title she was entitled to use when she reached the age of 18.