Why is the Queen not Mountbatten?
Even though Queen Elizabeth II had confirmed House of Windsor to be the family name when she succeeded to the throne in 1952 much to the disappointment of her husband, in 1960 she and Prince Philip decided that they would like their direct descendants to take both their family names as Mountbatten-Windsor.
Does the royal family use Mountbatten?
The surname Mountbatten has often been used by members of the royal family. The surname has most recently been given to Meghan Markle and Prince Harry's newborn daughter named Lilibet Diana. This is also the surname also used by their eldest son Archie Harrison.