Royal wedding: why won't Meghan Markle be called Princess Meghan after her wedding to Prince Harry?
The answer is stark and unapologetic: by British royal protocol, the American actress lacks "royal blood."
That is the reason why Meghan will not be called a princess after she marries Prince Harry on May 19.
In practical terms, the rule means that Megham Markle will be forced to follow the example of her future sister-in-law.
When Catherine Middleton and Prince William were pronounced "wife and husband" in 2011, she automatically became Her Royal Highness Princess William of Wales.
There is a strong chance that Meghan will become HRH Princess Harry of Wales.
So, officially at least, the British can forget about Princess Meg, just as there is no Princess Kate.
Princesses by right
Having "royal blood" allowed the younger sister of Queen Elizabeth II of England to be called Princess Margaret.
In the same way that the queen's daughter is Princess Anne and her granddaughters are princesses too: Beatrice and Eugenie.
Ancestry simply gave them the right to be princesses.
But her mother, Sarah Ferguson, was never Princess Sarah, and Sophie Rhys-Jones, Prince Edward's wife, is not Princess Sofia.
The rules also mean - to the dismay of many - that Lady Diana Spencer was never officially Princess Diana.
As BBC journalist Nicholas Witchell explained, when William and Kate got engaged in 2011, the royal family hasn't flourished for 1,000 years without finding a solution to this somewhat perplexing and nonsensical problem of what its members should be called.
From Buckingham Palace's point of view, titles are needed for family members who occupy peripheral, albeit prestigious, roles in the main business of the monarchy.
Between dukes and duchesses
The Queen's first-degree cousins are respectively the Duke and Duchess of Gloucester and Kent, and when her uncle left the throne to marry a divorced American in 1936, he became the Duke of Windsor.
Those duchies are often awarded through marriage, the BBC journalist points out, precisely because they are giving the new family member a renowned title without giving them the right to be princes or princesses.
So when Prince Andrew and Sarah Ferguson married in 1986, the queen gave him the title of Duke of York. She became the Duchess of York, a title she continues to hold despite her divorce.
In the same way, when Prince Edward married Sophie Rhys-Jones, he became the Earl of Wessex and his wife, the Countess of Wessex.
It could be possible that the queen will make the same decision in the cases of Kate and Meghan, and dust off a dukedom of the family that has been in disuse: Sussex (the favorite for Harry and Meghan). Those from Albany and Clarence are among the vacancies.
The exception to the rule
But as with many things connected with British royal protocol, there is always an exception to the rule: the queen's husband, Philip, is indeed a prince.
When he married the then Princess Elizabeth in 1947, King George VI made him "Duke of Edinburgh".
It was not until February 1957 that he became Prince Philip, that the Queen "agreed for him the style and title of Prince of the United Kingdom."
The monarch could turn Kate and Meghan into princesses, but due to the rigidity of the traditions surrounding British royalty, it might take a long time.
