Image Source: Getty / WPA Pool
The title Princess of Wales may best be associated with Princess Diana, but one day, the title will likely pass to Kate Middleton. Since the 1200s, the title Prince of Wales has been given to the British heir apparent, with the wife of that heir becoming the Princess of Wales. When the queen passes, Charles will become king and William the heir apparent, thus putting William in line to become the Prince of Wales and Kate the Princess of Wales.
But before this happens, the monarch (aka Charles) must grant William the title Prince of Wales as a "personal honor." That means Kate won't become the Princess of Wales automatically once the queen dies, but rather after Charles gives William the title. Charles, for example, did not become the Prince of Wales until his mother granted him the title in 1958, when he was 9 years old. And he wasn't "crowned" Prince of Wales until July 1, 1969, at the age of 20. Because he was already the Prince of Wales when he married Diana, she became the Princess of Wales automatically by marriage.
The crowning — called an "investiture" — is part of the tradition surrounding the title, and it is almost like a royal wedding or coronation. More than 500 million people watched on TV as Charles was crowned Prince of Wales in the '60s. Author Sally Bedell Smith describes Charles's investiture in her new biography about the prince: "The queen crowned her son with a highly stylized and bejeweled coronet and draped him with a cape of purple velvet." At the ceremony, Charles swore to be the queen's "liege man of life and limb and die against all manner of folks." We can expect some over-the-top royal drama when it's William's turn.
Prince Charles was crowned the Prince of Wales in 1969. Image Source: Getty / Hulton Deutsch
Following Prince William's investiture as Prince of Wales, it's likely Will and Kate would no longer be called the Duke and Duchess of Cambridge but rather the Prince and Princess of Wales. Of course, there's a chance Kate will decide not to use the title. The current "Princess of Wales" is technically Prince Charles's wife, Camilla. Instead of using that title, however, Camilla goes by one of her other titles, the Duchess of Cornwall, out of respect for Princess Diana. (Camilla and Charles famously carried on an affair during Charles and Diana's marriage, so there would surely be public outcry if Camilla used Diana's title.) Still, there's a good chance Kate will see the Princess of Wales title as a way to carry on Diana's legacy, when the time comes. And Catherine, Princess of Wales, does have a nice ring to it.