The Inverted Jenny is one of the world's most recognised stamps. Much has been written about its discovery, a Hollywood superstar is believed to own an example, and the stamp even appeared in the 1980s hit movie Brewster's Millions.

And now the finest 'never hinged' example will form the centrepiece of an auction at the American Philatelic Society Annual Convention in Pittsburgh on August 7, 2009

It's the first time this stamp has been on the market in 50 years and according to the auctioneer "in all likelihood it won't come on the market again for at least another 50."

The 24c stamp is famous for the upside down Jenny aircraft pictured on the stamp. Its appeal has lead the stamp to not only be one of the most famous stamps in the world, but also one of the most famous collectibles in the world.

Only one single sheet of 100 was ever discovered. A block of four sold for over $2.7m at auction in 2005. Another appeared at auction in 2006 and is believed to have been snapped up by a household name movie star as part of a long term investment strategy.

Of course the prices realised all depend on the quality of the individual stamp. This particular stamp is recognised as the finest available and is expected to sell in excess of $900k.

Another example sold at auction in New York in November 2007 for $977,500, the following month a similar quality example sold for $825,000 - to the Wall Street broker who lost the auction the previous month.

We'll be bringing you the auction result in the next few days.

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