Kate Middleton, Prince William barred from having custody of their children

For us common folks, a lot of the British royal family rules sly straight above our heads.

Amongst those incomprehensible guidelines is one that prohibits royal parents like Kate Middleton and Prince William from having custody of their own children—Prince George, Princess Charlotte and Prince Louis.

For technical reasons, the Duke and Duchess of Cambridge do not have custody over any of them, courtesy of a 300-year-old rule, reports News.com.au, as per Harper’s Bazaar.

Royal historian and founder of Royal Musings blog Marlene Koeing told the publication: "The sovereign has legal custody of the minor grandchildren.”

"This goes back to King George I [who ruled in the early 1700s], and the law’s never been changed. He did it because he had a very poor relationship with his son, the future King George II, so they had this law passed that meant the King was the guardian of his grandchildren."

As per the outlet, the law had passed back in 1717 and was legislated once more in 1772 and has not yet been changed.

As per this rule, Queen Elizabeth II was the legal custodian of Prince William and Prince Harry while they were minors. It remains unclear whether the rule applies for great-grandchildren as well since King George I did not have any when the rule was first set in motion.

Therefore, when Prince Charles inherits the throne, he will be the one to have custody of his grandchildren.

According to the original text of the law, having custody means the sovereign is the one responsible for the minor’s upbringing, travel and education.

With Harry and Meghan Markle out of the royal family, the law perhaps does not apply to them but for the Cambridges, their three children are certainly not under their custodianship.