Prince William often uses code names or secret names on occasions when he wants to travel, go out to enjoy or walk incognito, like the time when he was still Kate’s boyfriend and they decided to spend a vacation in the paradisiacal Seychelles islands.
According to what the writer Marcia Moody related in her book Kate: biography of a princess, both used names other than their own. “They stayed at the Desroches Island Resort, registered under the names Martin and Rosemary Middleton” taking advantage of her family name. In fact, on that occasion the author says that the two had gone to those islands after having gone through a crisis and reconciled.
However, these pseudonyms are no longer used today, although we do not know if it was imposed by the Palace, or if it is rather a decision that the couple has taken given the popularity of Kate Middleton and her surname in recent years, so it is not at all unreasonable. Although in any case, changing these pseudonyms for others less known was a great success.
On the other hand, now the codename that Prince William uses is Danni Collins, while Princess Kate’s is Daphne Clark. And if we analyze well both names, we can realize that the initials of each one coincide with their title of Duke and Duchess of Cambridge.
Although they are not the only ones who use other names to protect their privacy, as Meghan Markle and Prince Harry also have this practice well ingrained.In their case, they use Davina Scott and David Stevens, which, by the way, also coincide with their title of Duke and Duchess of Sussex.