Kate Middleton sparks royal fury amid usage of 'Princess' title: 'Not born a royal!'

Kate Middleton has invited the wrath of royal fans who have slammed her for using the 'Princess' title on birth certificates of her kids: George, Charlotte and Louis.

The Duchess, who married into the royal family, is listed as "Princess of the United Kingdom" on the documents, despite not being a royal by birth. 

This irked royal fans who took to Twitter to express their displeasure. One user said: "Princess of the United Kingdom?!"

Another one wrote, "Have they technically got that wrong? She is not a Princess of the United Kingdom as she was not born a royal."

Kate is not "Princess Kate" or "Princess Catherine" as only daughters born into the royal ramily, like Princess Charlotte or Princess Beatrice, are allowed to use those stylings.

The Duchess's title will likely change when Prince Charles becomes King. Kate will then be referred to as the Princess of Wales, like Princess Diana.