From chesshistory.com: Following press reports that Nimzowitsch had issued a world championship challenge, Capablanca wrote to him from New York on 21 September 1926 that he had received no direct word and giving him until the end of the year to post a forfeit for a match, failing which he would take up Alekhine’s challenge.
On page 2 of The World Chess Championship 1948 (London, 1949) Harry Golombek stated, in a discussion of possible challengers for the world title in the 1920s, that Nimzowitsch ‘does not seem to have been really serious in his claims, and confined his pretensions to having visiting cards printed on which appeared his name and the title “Crown Prince of the Chess World”’.
This may seem questionable, and we wonder, in particular, whether the well-known ‘visiting-card’ story is true. Has anybody seen one? And when did Nimzowitsch give himself the title ‘Crown Prince’?
The only contemporary reference we can offer is a second/third-hand one, i.e. the BCM’s report on the Frankfurt, 1930 tournament (November 1930 issue, page 403): ‘In the last six rounds [Nimzowitsch] made a clean score. E.S. Tinsley, in The Times, says that he now chooses to call himself “the Crown Prince of the chess world”.