Most people assume that if you’re the future King of England, your last name is just "Prince." Or maybe "King-in-Waiting." Honestly, the reality of the surname Prince William uses is way more complicated and, frankly, a bit of a headache for bureaucratic systems like the Passport Office or the DMV.
He doesn't have one. Well, he does. But he doesn't have to use it.
Royal naming conventions are a messy blend of ancient decrees, military traditions, and geographic titles that shift every time someone dies or gets promoted. If you’ve ever wondered what William writes on a legal document or how he signed his name at school, you're looking at a naming system that hasn't changed much since the middle of the 20th century, despite how modern the Prince of Wales tries to appear.
The Mountbatten-Windsor Confusion
Back in 1917, King George V got tired of sounding too German during World War I. He ditched "Saxe-Coburg-Gotha" and picked "Windsor." It sounded British. It sounded like a castle. It worked.
Fast forward to 1960. Queen Elizabeth II and Prince Philip decided they wanted their direct descendants—the ones who weren't styled as Royal Highnesses—to have a way to distinguish themselves. They combined her house name, Windsor, with his adopted surname, Mountbatten.
Thus, Mountbatten-Windsor was born.
Technically, if William ever needs a "hidden" last name for a legal filing where his title isn't sufficient, this is the one that sits on the shelf. But here’s the kicker: he almost never uses it. It’s like a tuxedo in the back of the closet. It’s there, but he’s usually wearing something else.
Why "Wales" Was His Identity for Decades
For the vast majority of his life, William didn't go by Windsor. When he enrolled at Ludgrove School and later Eton, he was known as William Wales.
Why? Because his father, Charles, was the Prince of Wales.
In the British Peerage, the children of a Duke or a Prince often use their father’s highest title as a temporary surname. It makes things easier for teachers and classmates. When he joined the Royal Air Force and served as a search-and-rescue pilot, his name tag didn't say "His Royal Highness." It said Flight Lieutenant William Wales.
Imagine being in a helicopter, looking at the guy next to you, and his name tag is basically just his dad's job title. It's weird, but in the military, it provided a shred of normalcy. He was just one of the guys, sort of.
The Shift to Cambridge
Everything changed in 2011. When William married Catherine Middleton, the Queen gave him a new title: The Duke of Cambridge.
Suddenly, "Wales" was out. "Cambridge" was in.
When Prince George, Princess Charlotte, and Prince Louis started school at Thomas's Battersea, they were registered with the surname Cambridge. For a decade, that was the family brand. If you were looking at a school register, you’d see "George Cambridge" right next to "Smith" or "Jones."
💡 You might also like: Sofia Carson and Dove Cameron: What Really Happened to the Descendants Duo
It’s a practical solution to a very posh problem.
The Current Reality: The Surname Prince William Uses Today
In September 2022, following the death of Queen Elizabeth II, the deck was shuffled again. Charles became King. William became the Prince of Wales.
The surname Prince William and his family use effectively reverted to Wales.
If you look at his children's social media or school mentions now, they are George Wales, Charlotte Wales, and Louis Wales. It’s a bit of a circular journey. He started as Wales, spent a decade as Cambridge, and is now back to Wales.
But wait. There’s a catch.
When William eventually ascends the throne, he will likely stop using a surname entirely. British monarchs typically sign official documents with their first name followed by an "R" for Rex (King) or Regina (Queen). So, he will just be William R.
The Passport Problem
You might think a guy who travels this much has a passport filled with stamps and a very clear surname on the data page.
Actually, the King doesn't even have a passport. Since British passports are issued in the name of the Monarch, the King doesn't need one to identify himself. However, William is not yet the King.
William does have a passport. While the specific details are kept private for security, it is widely understood among royal experts like Marlene Koenig that his travel documents reflect his current title. He doesn't just put "N/A" in the surname box.
Misconceptions About the House of Windsor
A lot of people think "Windsor" is the only option. It’s not.
There is a distinction between the name of the Royal House and the surname of individuals.
- The House is Windsor.
- The surname (if needed) is Mountbatten-Windsor.
If William's sister, Princess Anne, wanted to get married without using her titles, she would use Mountbatten-Windsor. But William is a "Royal Highness." According to a 1960 declaration, those with the style of HRH Prince or Princess generally do not need a surname at all.
They are simply who they are.
What Happens in the Future?
When William becomes King, the "Wales" surname will likely pass to Prince George. George will become the Prince of Wales, and his children will use that name until he becomes King, and the cycle repeats.
It's a rolling identity.
It's also worth noting that William has the power to change this. Just as George V changed the name to Windsor to distance the family from Germany, William could, in theory, decide that "Wales" or "Cambridge" or something entirely new should be the official family name.
He probably won't. The British monarchy thrives on the "if it ain't broke, don't fix it" mentality, even if it confuses the rest of us.
Summary of Names Used by Prince William Over Time:
- Birth to 2011: William Wales (Used in school and military)
- 2011 to 2022: William Cambridge (Following his creation as Duke of Cambridge)
- 2022 to Present: William Wales (Following his creation as Prince of Wales)
- Official Legal Surname: Mountbatten-Windsor (Rarely used)
Understanding the "Why"
The reason this feels so confusing is that surnames are a relatively modern invention for the peasantry, whereas Royals have always been identified by their lands. In the Middle Ages, you were "William of Normandy." You didn't need a last name because everyone knew which William you were talking about based on what you owned.
William is effectively "William of Wales" right now.
It’s an Echo of feudalism.
If you're trying to track the surname Prince William for genealogical reasons or just out of curiosity, the best way to think about it is that his "last name" is whatever his current territory is.
Actionable Insights for Royal Researchers
If you are writing about the Royal Family or researching their history, keep these specific rules in mind to avoid common errors:
- Distinguish between House and Surname. Use "House of Windsor" for the institution and "Mountbatten-Windsor" for the rare instances a personal surname is required for descendants of Elizabeth II and Philip.
- Check the Date. A royal's "surname" changes with their title. If you are writing about William in 2015, use Cambridge. If you are writing about him in 2025, use Wales.
- Ignore the "Prince" as a Surname. In database entries, "Prince" is a title/prefix, not a surname. Using it as a last name is a frequent data entry error.
- Look at Military Records. These are the most reliable places to see how the Royals handle surnames in the "real world." Search for "Wales, W." in historical RAF or Army rosters for primary source evidence.
The fluid nature of royal names is a feature, not a bug. It allows them to remain distinct from the general population while still fitting—roughly—into the boxes required by modern society. Whether he's Flight Lieutenant Wales or the Duke of Cambridge, the man remains the same, even if his paperwork is a nightmare.
Next time you have to fill out a long form at the doctor's office, just be glad you don't have to decide which of your three historical surnames to use.
To keep your records accurate, always cross-reference the date of an event with the specific title held by the Royal at that time. Titles are the primary identifier; surnames are merely a secondary convenience. For those interested in the legal mechanics, the 1960 Order in Council remains the definitive document on the use of Mountbatten-Windsor. Reading the text of that declaration provides the clearest picture of how the family views its own identity.
Stick to the titles, and you'll rarely go wrong.