Because he was King.
She named him George, after his grandfather. When he became King of Great Britain he was King George III (his grandfather was King George II)
George III
King George III
King George III
The King of Great Britain, King George III.
King George III
King George III of England
King George III
King George III
King George III George III (George William Frederick).
King George lll
King George III was the King of England from 1760 to 1820.