There is only one case of the oldest surviving son of the Prince of Wales marrying before his father succeeded to the throne: the future George V who married Mary of Teck in 1893. He had already been created Duke of York a year earlier, shortly after the death of his older brother brought him directly in line of succession to the throne.
In recent years, several royal princes who did not already have a title were given one upon marriage, including Prince Andrew, who was created Duke of York when he married in 1986. In a break with precedent Prince Edward was created Earl of Wessex; at the same time it was announced that he will be given the title Duke of Edinburgh when that title, currently held by his father, reverts to the Crown. According to The Daily Telegraph, it is expected that William will be offered a dukedom on his marriage, allowing his wife to be styled as a duchess. In an interview with This is Sussex, Charles Kidd, editor of Debrett's, said that the title most likely to be bestowed on Prince William on the eve of his wedding was Duke of Sussex, although he added that other available dukedoms are Windsor, Clarence, Cambridge, Kendal, Avondale, and Strathearn.
In Letters Patent dated 21 August 1996 (shortly after the divorce of the Prince and Princess of Wales) it was acknowledged that "by convention the wife of the son of a sovereign of these Realms the wife of a son of a son of a Sovereign and the wife of the eldest living son of the eldest son of the Prince of Wales is entitled to the style title or attribute of Royal Highness". If William were not given a title then, after the wedding, Middleton would, by convention, be known as Her Royal Highness Princess William of Wales taking her husband's first name on marriage (as with Princess Michael of Kent). If however William is given a title, she would be known as "Her Royal Highness the Duchess [or other rank if appropriate] of N".
In December 2010, it was reported in The Daily Telegraph that William did not wish to receive a dukedom, preferring to remain simply "Prince William" while also wanting Middleton to become "Princess Catherine". It was suggested that this caused a dilemma for the Queen because princesses traditionally receive titles like that through birth instead of marriage. If the Queen does break tradition, royal biographer Kenneth Rose believes Princess Michael of Kent would then also ask for a non-traditional title like "Princess Marie-Christine" too.