Found the article :
In 2005, Elizabeth II changed the order of precedence for private occasions, putting Camilla, Duchess of Cornwall, fourth in the order of precedence, after herself, Anne, Princess Royal, and Princess Alexandra, contrary to the usual position of the heir's consort. Charles's first wife, Diana, Princess of Wales, had ranked above the Princess Royal and Princess Alexandra.[3] The Duchess of Cornwall continues to rank second in the order of precedence at official occasions, such as state dinners.
Princesses of the Blood Royal, such as Princess Beatrice of York and Princess Eugenie, rank above Catherine, Duchess of Cambridge and Meghan, Duchess of Sussex, when the latter are not accompanied by their husbands. When the Duchess of Cambridge or Duchess of Sussex are joined by their husbands, the roles are reversed with the duchesses outranking the princesses
Why is princess Alexandra so high? She's 53rd in line (I googled!) So E and B are earlier in succession. So shouldnt they be before her? I can understand non bloods being later as they can't inherit (although must be a pain to keep track) but Alexandra makes no sense.