Why was Diana never referred to as "Princess Charles"

I thought the correct way to address the spouse of a Prince was with the Prince’s name, unless that person has the title “Princess” in their own right (by birth, for example). For example: Princess Michael of Kent. Michael isn’t her first name. Her real name is Marie-something-and-something-else.

Therefore, I thought that Diana was supposed to have been correctly named: “Lady Diana, Princess of Wales”, or even “Princess Charles of Wales”, Lady being her title in her own right, yet, I’ve seen her referred to as “Princess Diana”. Were people just being ignorant, or were they ignoring proper convention because Diana was popular?

Also, why is Prince Phillip only a Prince? Is the same reasoning as above?

The Master speaks: A king’s wife is a queen, so why is Elizabeth II’s husband still only Prince Philip?

Baroness Marie-Christine von Reibnitz, of Austria, daughter of Baron von Reibnitz and the former Countess Marianne Szapary.

Prince Charles’ official title is actually HRH The Prince of Wales, together with a whole lot of subsidiary titles. Officially he should not be called “Prince Charles”, any more than HRH the Duke of York should be called “Prince Andrew”, HRH the Earl of Wessex should be called “Prince Edward” or HRH the Princess Royal should be called “Princess Anne”. It’s just a convenient shorthand.

So, during their marriage, officially Diana was HRH The Princess of Wales, usually simplified to “Princess Diana”. She lost the HRH title after the divorce.

…but I thought the sons and daughters of princes are princes and princesses in their own right, correct? The children of princes are likewise princes and princesses. That’s why “Prince Michael” is a Prince and not a Lord, even though his dad was never king of anything. He also isn’t the Duke of Kent, that’s his brother.

You automatically get the title “Prince” at birth, same for “Lord” or “Lady” in the same way “Mr.” or “Ms” is a title. Prince Charles was a Prince long before he was the Prince of Wales. How would you have addressed a letter to Charles as a child? He certainly wasn’t “Master Charles” or “Lord Charles”.

So, if this is true, I think comparing the usage of “Prince” with Charles to the usage of “Princess” with Diana is like comparing apples and oranges.

yes.
I would bet most people assumed “she married a prince, that makes her a princess” and incorrectly stuck the word in front of her first name.

Not necessarily. Princess Anne’s children are merely lord and lady, IIRC. I don’t know the laws of titles, but I do believe they’re not automatic.

I believe Charles would have been addressed as, HRH, Prince Charles?

I believe Cunctator’s point is that both “Prince Charles” and “Princess Diana” were technically incorrect titles, regardless of whether Charles or Diana was or was not a princess. In both cases, they were just convenient shorthand used in common speech. Obviously you can’t apply technical rules to something that’s technically incorrect to begin with. If “Prince Charles” is incorrect, why would Princess Charles necessarily be any more correct?

It may have gained currency by analogy to the use of the titles King and Queen, which have a generally accepted usage because, of course, the technicalities of each King or Queen could depend on the usage in their own nation, and not even other kings might know the rules. The US governemnt wouldn’t have addresses a letter to “King Kamahameha”, though he himself used that title (and not the more specific titles of European royalty); it would have at the very least referred to him as His Royal Majesty King Kamehameha of the Hawaiian Islands (by its own rules)

You wouldn’t have properly addressed a letter to him to “Prince Charles” any more than you could properly address Diana as Mrs. Prince Charles, even though she really was a Mrs, and he really was a prince. You would however have been quite correct to address a letter for the artist-soon-to-be-known-as-Prince to " Prince Rogers Nelson" (his name at birth) or to his wife as Mrs. Prince Rogers Nelson, though neither is royalty. Perhaps more appropos, “Lawyer Malone” (the American football player) is a correct address, but though we may refer to “Lawyer Smith” in some parts of the US, as a shorthand (e.g ol’ Lawyer Smith up and died today) by analogy to Doctor, it is not the proper address for an attorney.

Princess Anne’s children are merely Mr. & Mrs. as their father has no title and titles descend through the male line (with some exceptions)

This is how I understand the titles to work:

  1. All the children of a reigning monarch are called HRH Prince X or Princess Y from birth. The eldest son is usually created Prince of Wales around age 16 or so. His wife is then called the Princess of Wales. The eldest daughter may be given the title Princess Royal (if it’s free), at the monarch’s discretion. As the monarch’s younger sons grow up, they are generally given a peerage, after which they’re known by that title e.g. HRH the Duke of York. The wives of the younger sons of the monarch are thus called by their husbands’ titles e.g. HRH the Countess of Wessex (wife of Queen Elizabeth’s youngest son). Daughters of a monarch retain their HRH style, but take their full name from their husband e.g. HRH the Princess Royal (Mrs Timothy Laurence) or HRH Princess Margaret, Countess of Snowdon (the Queen’s deceased yonger sister).

  2. The HRH style is also used by all of the children of the sons of a monarch e.g. TRH Princesses Beatrice and Eugenie of York (daughters of HRH the Duke of York), or TRH Prince Michael of Kent and Princess Alexandra of Kent (children of HRH the Duke of Kent, son of King George V). The wife of HRH Prince Michael of Kent (formerly Baroness Marie-Christine whatshername) is known as HRH Princess Michael of Kent. The husband of HRH Princess Alexandra of Kent (who is a bloke called Sir Angus Ogilvy), doesn’t get any extra title on the normal grounds that an inferior wife gets pulled up by her husband’s superior rank, but an inferior husband doesn’t get pulled up by his wife’s superior rank.

  3. Children of the daughters of a monarch take their titles from their fathers. So the children of HRH the Princess Royal are simply Mr Peter and Miss Zara Phillips, because their father was plain old Mr Mark Phillips. Also, the children of the late HRH Princess Margaret are called Viscount Linley and Lady Sarah Chatto i.e. they take their rank and style as the son and daughter of an earl, their father Lord Snowdon.

  4. The HRH style does not flow into the third generation, so the grandchildren of the sons of a monarch take their style from their father e.g. the children of TRH the Duke and Duchess of Kent (i.e. great grandchildren of King George V) are called by the normal courtesy titles given to a non-royal duke’s children. I can’t remember their names, but they’re something like Lady X Windsor etc.

I think that’s it, but I could be wrong because it’s pretty convoluted. Also, these are the rules for the British royal family. Other countries will have different rules.

when diana married charles, the prince of wales she became diana the princess of wales.

william and henry at birth became prince william of wales and prince henry of wales. no “the” for them.

should they marry at the tender age they are and have no other titles given to them, their wifes would be princess william of wales and princess henry of wales.

when diana divorced charles she became diana, princess of wales, no “the.”

I forgot to add in my earlier reply that the rules about royal titles, if applied strictly to Charles at his birth in 1948, would have meant that he was not a prince from the moment of his birth. This was because, although he was born the grandson of the reigning monarch King George VI, Charles was a son of the monarch’s **daughter ** (HRH Princess Elizabeth) and not a son of the monarch’s son. He was thus not automatically entitled to the title HRH and in the normal course of events would have taken his title from his father the Duke of Edinburgh. In order to avoid this and to make sure that HRH Princess Elizabeth’s child was entitled to the title HRH from birth, on 9 November 1948, less than a week before Charles’ birth, HM King George VI issued letters patent under the Great Seal ordaining that any children born to the Duke and Duchess of Edinburgh (i.e. Princess Elizabeth) would have the title of prince or princess and the style of Royal Highness.
This is a useful site for all of the details on this topic (particularly questions 25, 26, and 27).