Royal enthusiasts remain puzzled by the supposed nickname that William, Prince of Wales, uses for his younger brother Harry.

King Charles III, previously the Prince of Wales, and his late ex-wife, Diana, Princess of Wales, welcomed Harry into the world on 15 September 1984.

At that time, the former couple announced that Harry’s official title would be Prince Henry Charles Albert David Wales.

However, friends and family simply know him as Prince Harry.

Over time, people have become so accustomed to calling the Duke of Sussex ‘Harry’ that many have forgotten it isn't his legal name.

So, why does the 41-year-old claim his elder brother, William, calls him Harold instead?

This question was initially raised by a Reddit user who wrote: “I'm listening to Spare, and [William] always calls him Harold. His given name is Henry. Why?”

The late Princess Diana announced that although her child's name was 'Henry', he would be known as 'Harry' (Yui Mok - WPA Pool/Getty Images)

People have been discussing why William might call his brother Harold, even though his name is Henry and he prefers ‘Harry’.

“Nickname? I think nicknames are quite common in most families, and what may start as a teasing nickname can become affectionate over time,” one person remarked.

Another puzzled user challenged: “But Harry is already the nickname. Are you suggesting the nickname has its own nickname? I suppose that could work.”

“Just a nickname, I think. It's quite amusing when the legal version of a name is shorter than its diminutive,” a third commented.

“My best friend's legal name is Clara, and I call her Clarissa just for fun. (Of course, Clara is not actually a diminutive of Clarissa, but it’s the only example I can think of right now).

“I know many people who do similar things. Bill Idle is many things, but I doubt he's a cartoon villain. Harry calling William 'Willy' is also quite amusing.”

Harry's claim that his elder brother had nicknamed him ‘Harold’ first surfaced when a passage from his 2023 memoir Spare was published in The Guardian.

The excerpt recounted an alleged altercation between the royal brothers, with the father-of-two writing that William had ‘grabbed him by the collar’ before tearing his necklace and knocking him ‘to the floor’.

The Duke of Sussex claimed his older brother calls him 'Harold' (Julian Parker/UK Press via Getty Images)

In the excerpt, Harry wrote that William said: "You don’t need to tell Meg [Meghan Markle] about this", to which he replied: “You mean that you attacked me?"

To this, William allegedly responded: “I didn’t attack you, Harold.”

But ‘Harold’ apparently isn’t Harry’s only alternate nickname.

He has mentioned that while his close friends call him ‘H’, his wife, Meghan, Duchess of Sussex, refers to him as ‘Haz’.

The Cut reported in 2023 that during an appearance on The Late Show with Stephen Colbert, the author mentioned that others have called him ‘Baz, Bazza, Spike, and Bazzarooni’.

Meghan has also mentioned that their son, Prince Archie of Sussex, calls his father ‘papa’.

This is a nickname Charles also used to refer to his father, Prince Philip, Duke of Edinburgh, according to The Express.

“My dear papa was a very special person who I think, above all else, would have been amazed by the reaction and the touching things that have been said about him,” Charles wrote in a heartfelt tribute released after his father’s passing.

“And from that point of view, my family and I are deeply grateful for all that.”