You’d think the most famous man in Britain would have a straightforward ID card. But if you were to ask for Prince William’s last name, you wouldn't just get one answer. You’d get three. Or maybe none at all.
Most of us have a surname that follows us from the cradle to the grave. It's on our birth certificates, our mail, and our awkward high school yearbooks. For the heir to the British throne, things are a lot more fluid. Honestly, it’s a bit of a bureaucratic headache if you really think about it.
The Official Family Name: Mountbatten-Windsor
Technically, the "legal" surname for descendants of Queen Elizabeth II and Prince Philip is Mountbatten-Windsor. This name is a relatively recent invention, appearing in 1960. Before that, the family was just the House of Windsor.
Prince Philip, William’s grandfather, famously complained that he was the only man in the country not allowed to give his name to his own children. He felt like a "bloody amoeba." To keep him happy, the Queen issued a declaration. She decided that while the Royal House would remain Windsor, her descendants—specifically those who aren't HRHs or those who need a surname for things like marriage licenses—would use Mountbatten-Windsor.
It’s a mouthful. It’s also rare to see it in the wild. You’ll find it on official documents, like when William filed a lawsuit in France years ago or when Princess Anne got married. But William doesn't exactly go around introducing himself as "Will Mountbatten-Windsor" at parties.
Why He Was "William Wales" for Decades
For a huge chunk of his life, Prince William used a completely different last name. When he was at school at Eton and later at the University of St Andrews, he was known simply as William Wales.
Why? Because his father, Charles, was the Prince of Wales at the time.
In the British royal system, children often use their father’s title as a temporary surname. It’s a way to blend in. Well, as much as a future king can blend in while surrounded by bodyguards. When he joined the Royal Air Force and served as a search-and-rescue pilot, his uniform didn't say "Prince William." It said Wales.
👉 See also: Kim Kardashian and Serena Williams: What Most People Get Wrong
The Shift to "Cambridge"
Then he got married. In 2011, the Queen made him the Duke of Cambridge. Suddenly, "Wales" didn't fit anymore. For about a decade, his family essentially became "The Cambridges."
When his kids, George, Charlotte, and Louis, started school, they were enrolled as George Cambridge and Charlotte Cambridge. It was a neat, tidy way to handle the "last name" problem without making a huge fuss about their royal status every time a teacher took attendance.
What is Prince William's Last Name Right Now?
Here is where it gets interesting. Now that King Charles III is on the throne, William has inherited the title of Prince of Wales.
Because of this, the family has circled back. The kids are now George Wales and Charlotte Wales at school. William himself is back to using Wales as his professional designation.
So, if you’re looking for the most current, day-to-day answer, Wales is the winner. But if he were filling out a super-formal legal contract that required a "civilian" surname, he’d likely fall back on Mountbatten-Windsor.
Does He Even Need One?
Actually, usually not.
Most royals with the "His Royal Highness" (HRH) styling don't actually have a surname in the way you or I do. Their title is their identity. It’s similar to how a person might just be known by one name, like Madonna or Beyoncé, except William’s "one name" is a centuries-old territorial designation.
The 1917 Rule That Started It All
Before 1917, the British Royals didn't have surnames at all. They just had the names of their "Houses," which were usually German and very hard to pronounce.
During World War I, King George V realized that having a German-sounding name like "Saxe-Coburg-Gotha" was a PR nightmare while Britain was at war with Germany. He scrapped it and picked Windsor, after the castle. He declared that Windsor was now both the name of the Royal House and the official surname of the family.
It was a branding masterstroke. It made the family feel English, solid, and approachable.
Practical Takeaways for Royal Watchers
If you're trying to keep this straight, just remember these three rules:
- In School/Military: They use their father's highest title (currently Wales, previously Cambridge).
- On Legal Paperwork: They use Mountbatten-Windsor.
- In History Books: They belong to the House of Windsor.
The royal naming system is basically a mirror of their current rank. As William moves closer to the throne, the "Wales" name will eventually be dropped when he becomes King, as monarchs generally sign with just their first name and a Roman numeral.
For now, if you're writing him a letter or checking a flight manifest, "William Wales" is the most accurate "human" version you'll find. It’s a weird quirk of British history, but it’s one that has worked for them for over a century.
To get the most accurate sense of how these names appear in real life, you can look at the official circulars from the Royal Family website or check the registry at schools like Lambrook, where the younger generation is currently enrolled. These sources consistently show the transition from Cambridge to Wales following the change in the sovereign.