This stamp is one of the major Canadian rarities, it was issued in 1932. Approximately 8000 stamps were printed out of which 50 of the stamps depicted inverted surcharge in red ink.
This stamp was printed to create a mail that transported abroad the Dornier Do-X flying boat on its return flight from Canada to Germany. There are said to 20 to 40 surviving specimens of this rare error.
The most marvellous example of this stamp is sold for 30,000 dollars at Kelleher Auctions in March 2014.
Image Courtesy: stampauctionnetwork.com