When asked your name, it’s standard to follow with your first and then last. The British royal family only goes by their name and their title, but do not technically have a last name. The more you think about it, the more mysterious it seems.
Why do they forego a last name? The simple answer: they don’t need a last name. Their first names are iconic and recognizable enough that they needn’t a last name for others to know who they are.
The historical answer is that they haven’t ever had a last name and have only answered to their first name and the house from with they hail. Back during King George V’s reign, he deemed “Windsor” as the family surname, which was taken from the House of Windsor.
To this day, if necessary, the Queen will go by Windsor. Her and Philip’s children go by their combined names, Mountbatten-Windsor. Though there are many rules in the Royal household, taking ownership of a particular surname isn’t necessary.
When Prince William and Prince Harry were attending school, they went by the surname “Wales” because their father, Charles, is the Prince of Wales. William and Henry Wales do have a nice ring to it though, don’t they?
I’ve never heard of a family having the option to forego a surname, but it’s highly interesting!