To members of the public they are known as Prince Harry and Meghan Markle, but to their royal aides and bodyguards they are just plain "David Stevens" and "Davina Scott".
It has been revealed that the famous couple are regularly given alternative monikers – secret code names that use the initials "DS" as a nod to their official title, the Duke and Duchess of Sussex, to prevent their contact details from falling into the wrong hands.
And as for Prince William and Kate Middleton, the couple are saved as the more modest "Danny Collins" and "Daphne Clark" in their aides' contact lists, Reports The Daily Mail.
The initials "DC" in the secret code names allude, of course, to the royal couple's title – the Duke and Duchess of Cambridge, reports the Daily Star.
"If anyone got hold of a phone belonging to a royal aide or security team member, they won't find Harry Windsor and Meghan's names in it," said a royal source, adding, "it is far too risky in the wrong hands. They get given code names but they are changed regularly for obvious reasons."
The code names were revealed at an event when one of Harry's aides told a worker that someone was trying to contact him.
But, failing to recognise the name on the assistant's mobile, the confused worker asked why the person on the line wanted to speak with him.
The source added: "Imagine the surprise he got when he heard Harry's voice on the other end of the line."
However, while members of the royal family are known by their secret code names to bodyguards and aides, when in private with their loved ones, they refer to each other by at least one nickname.
The Queen is known as "Gary" courtesy of Prince William who, as a youngster, struggled to pronounce "granny" and would call her Gary instead.
And Prince William's son, her great-grandson Prince George, has reportedly nicknamed the monarch "Gan-Gan".
Prince Charles is said to call Meghan Markle 'Tungsten' after the metal, because of her "tough and unbending" nature.
Kate Middleton and Prince William use terms of endearment by referring to each other as "darling" and "babe", while Meghan was recently overheard calling Prince Harry "my love" while watching the hit West End musical Hamilton with him.