The Squirrel Chronicles

The royal family is known as the House of Windsor. This was adopted in 1917, and before that there was no general use of any family name, though strictly they were Saxe-Coburg Gotha after the death of Queen Victoria, and Hanover before that (exactly what family name the House of Hanover had has never really been settled). Under the Tudors and Stuarts the family or house name was more commonly used.

Strictly a member of the Royal Family who is a prince or princess doesn't have a surname, and it is only with the arrival of more distant members of the family without royal titles that the issue arises. In Continental royal families everyone is a prince or princess, in the House of Windsor only the children and grandchildren, and the eldest son of the eldest son of the Prince of Wales, are so styled. So we now have people like Lord Nicholas Windsor, son of the Duke of Kent (and a great-grandson of King George V), who use the family name Windsor.

Since 1960 the rule has been that descendants of Queen Elizabeth II shall bear the suurname Mountbatten-Windsor, though the Royal Family remains officially the House of Windsor. This new surname will only appear with the grandchildren (if any, and in the male line) of Prince Harry.
 

That is seriously the most confusing thing I have ever heard. Even more confusing than Human Physiology.
I need to address this from a functional, applicable context...
So when Prince William and Harry went to school, and the substitute teacher called attendance, they didn't have a last name?
it was just "William" or "Harry?"
Or "William House of Windsor"?

Or when Diana walked herself down the road to the local elementary school to enroll her kids in kindergarten, she just told them
"Oh yes, William. Just William is his name"
????????????
 

They call them "Your Majesty" to their face, and "those annoying little fuckers" when they are not around. I think the drivers liscense says William Windsor.