Queen Elizabeth had to overturn an old royal rule in order to ensure her great-grandchildren were given their titles from birth.
When Prince Louis was born in 2018 he was automatically bestowed with an HRH title, as his older siblings Prince George and Princess Charlotte had been.
The youngster’s official full title is His Royal Highness Prince Louis of Wales, quite impressive given he has only just celebrated his sixth birthday.
However he only received his royal title thanks to his late great-grandmother Queen Elizabeth implementing a change to one rule that had been in place since 1917.
Over one hundred years ago the then-monarch, King George V, set out guidance explaining which members of the Royal Family would qualify for a title and which would not.
He made the decision that all of the sovereign’s children would automatically be a Prince or Princess, as well as any grandchildren born through the male line
But his rule did not apply to any of the monarch’s great-granchildren, which would have included George, Charlotte and Louis when they were born.
Ahead of George’s birth in July 2013 the late Queen decided to amend the rule so that the future King would be born with a royal title.
This change was then extended to Charlotte and Louis when they arrived in May 2015 and April 2018 respectively, and will likely apply to the future great-grandchildren of any monarch
Even if the late Queen had not made the change, the Wales children would have inherited their titles once their grandfather Charles became King.
His Majesty and Queen Camilla will be appearing at Trooping the Colour on June 15, and while Prince William is likely to attend Princess Kate will remain away.
She has been absent from public life while she receives preventative chemotherapy, as she announced her cancer diagnosis via a touchingly personal video message in March.