Queen Elizabeth II
Queen Elizabeth II is seen at the Chichester Theatre while visiting West Sussex on Nov. 30, 2017, in Chichester, United Kingdom. Getty Images/Stuart C. Wilson

Queen Elizabeth has been given a code name that is used to refer to her ahead and during her royal visits. According to a source, the code name has to be memorable and anonymous.

Instead of calling Her Majesty as Queen Elizabeth, the monarch, and other names, she is simply referred to as “S.” The letter is the shortcut of the Queen’s code name, “Sharon.”

Royal historian Hugo Vickers said that it is indeed possible for the Queen to be given code names when she’s doing her royal duties for her own safety and security. But Vickers also said that the letter “S” may also mean something else.

“The purpose of any sobriquet is that it should be anonymous and memorable. If it can also be a bit mischievous and therefore all the more memorable, then that makes sense… Although S might simply stand for Sovereign of course,” he said.

Meanwhile, the Queen isn’t the only member of the royal family who uses a code name. A palace insider previously told Daily Star that Prince William and Kate Middleton also go by different names to protect their privacy.

The Duke and Duchess of Cambridge are sometimes referred to as Danny Collins and Daphne Clark. They also go by the initials “DC,” which is a reference to their official title as the Duke and Duchess of Cambridge.

Prince Harry and Meghan Markle also go by the code names David Stevens and Davina Scott, respectively. “DS” stands for the Duke and Duchess of Sussex.

According to the insider, the use of code names makes it possible for the royals’ bodyguards to transport the members of the British clan from one place to the next with ease. The code names are also used to ensure that the contact numbers of the royals won’t be made public in case they lose their phones.

“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. It is far too risky in the wrong hands. They [are] given code names but they are changed regularly for obvious reasons,” the source said.