Edwardian or Edwardian?

Last year our distinguished colleague Professor Sir Christopher Ricks suggested to me that the correct pronunciation—or perhaps the most socially ambitious (not necessarily the same thing)—of the term Edwardian is not, in fact, like “accordion” but like “guardian” instead. Deeply skeptical, I hastened to check the first edition of the OED, itself a glorious monument to the Edwardian age, and found that they unequivocally gave the pronunciation of Edwardian like accordion. However, in the second edition and the current online entry (because they have a slightly worrying habit of revising and altering these from time to time) they are wavering, and now give Edwardian like accordion, but “also” like guardian. This seems to me irritatingly non-committal. I am not quite sure what it means, except that Edwardian like guardian was apparently unknown to the OED in its heyday, so I wonder where, when, or with whom the slightly affected later pronunciation originated. It has a vaguely Bertie Wooster-ish, Elsa Maxwell-ish, Wallis Simpson-ish, Duke-of-Windsor-ish quality, but who would know for certain? And what would The Queen say?