I was wondering why they say: Prince William and Kate Middleton, Prince Harry and Meghan Markle instead of Prince William and Kate or Kate Windsor, Prince Harry and Meghan or Meghan Windsor? Why keep there maiden names, no other married women do?
Yet Prince Phillip is called a Prince, why isn't he referred to as Prince Elizabeth? and why wasn't the House of Windsor changed to Mountbatten (since that is the Queens married last name?
The media are quite lazy when it comes to the titles for the royals.
They think that their readers won't know who they mean if they say HRH The Duchess of Cambridge - and so use Kate Middleton. Had they written HRH The Duchess of Cambridge, formerly Kate Middleton, for the six months or so after the wedding most people would be totally clear on who was meant but their jounalists are both sloppy and lazy and assume the general population are stupid as well.
Philip is a prince because a) he was born a prince and b) having given up that style in 1947 Her Majesty issued the Letters Patent creating him as a Prince of the UK. He had been created HRH in 1947 in the LPs creating him Duke of Edinburgh but not a Prince.
When the Queen married in 1947 she did change her name to Mountbatten as every other wife in the UK does but ... in 1952 when she became Queen Lord Mountbatten erroneously said that the 'House of Mountbatten now reigns'. It didn't as Elizabeth was born a Windsor and just like Victoria was a Hanover, Mary II and Anne were Stuarts and Mary I and Elizabeth I were Tudors the house name remained Windsor.
Queen Mary heard that the comment had been made and as her husband, George V, had changed the house name from Saxe-Coburg Gotha to Windsor, she wanted it to remain.
As a result the Queen issued a statement that the House name would be Windsor and changed her her children's name back to Windsor. That lead to Philip's famous comment that he was 'only an amoeba' as he wasn't allowed to give his name to his children - as every other man in the UK was allowed to do.
Then the Queen became pregnant with Andrew and a legal advisor told her that giving her children only her name made them effectively illegitimate as only the children of single mothers took their mothers names. She was advised to do something about it so she issued a new statement that the House name would remain Windsor but all of her descendants who needed to use a surname (other than the descendants of females whose children would take their father's names) would be Mountbatten-Windsor.
We see this used with Lady Louise who uses Windsor for short but whose official name, as evidenced in the CC on occasion and William's wedding programme is Lady Louise Mountbatten-Windsor. We also saw it when William and Kate too legal action in France where titles aren't permitted and they also used Mountbatten-Windsor.
Both Anne and Charles also used Mountbatten-Windsor on their first marriage certificates.
So the situation is that the House name is Windsor but the surname is Mountbatten-Windsor.