Had Edward VIII as King married Wallis Simpson she would, unless other arrangements were made, automatically have become Queen and would have been addressed as 'Your Majesty". There was a proposal floated before the final crisis was reached (see my Timeline at http://bolvbcw.blogspot.co.uk/2017/01/t ... -vbcw.html
) of a morganatic marriage, whereby by special arrangement, Wallis would not become Queen upon marriage, but would be given some other Royal Title (HRH The Duchess of Cornwall??). She would than have been addressed as "Your Royal Highness". Morganatic marriages had occurred in European Royal Families (i.e. Austro-Hungary and Franz Ferdinand), but were unknown in English royal history. The proposal was unacceptable to Baldiwn and the Cabinet as a whole, and thus abdication (or civil war!) became the only solution. By way of footnote, after the abdication, although Wallis became "the Duchess of Windsor" automatically upon marriage to ex-King Edward VIII (retitled "HRH the Duke of Windsor"), George VI refused to grant her the usual courtesy of a royal title i.e. HRH the Duchess of Windsor. Absent a Royal title, as a mere Duchess, Wallis would have been/was properly addressed as "Your Grace". There is some academic debate as to whether he had the right to deny such title to Wallis, and the refusal particularly rankled with Edward for the rest of his life. That said, George VI also (in effect) refused to grant Wallis the right to reside in England, so it was not the greatest slight...hope this helps.