INTERNATIONAL: Remember postage stamps? Well, one of the world's first, a rare “Penny Black”, is going up for auction next month at Sotheby's in London. It will have an estimate of over $8 million.

The Penny Black was the first postage stamp ever issued. The one on auction dates from 1840. Sotheby’s calls it "the earliest securely dated example of the first postage stamp." The stamp, which features that famous profile of Queen Victoria, is attached to a document dated 10 April 1840, from the archive of British postal service reformer Robert Wallace. What makes it so valuable is that date -10 April 1840.

That’s a few weeks before the Penny Black was issued at a flat rate from 6 May 1840. Whoever bought the stamp on auction would not have paid a flat rate, but the actual cost to deliver the document. Sotheby’s are saying it’s the most important piece of philatelic history in existence. Its owner, Alan Holyoake, says he’s surprised this much fuss wasn’t made over it before:

"So mass communication with the stamp had its birth and today we don't think about it, do we? We communicate as if it's just a natural right. Prior to the 6th of May 1840 it was not. You could not afford to do what you do today. So, yes, it's the first time, yes, I believe the most important thing in philately, but I believe in history and social history it is far more important and I'm surprised that has been totally ignored."

The stamp is one of three Penny Blacks believed to have survived from the very first sheet of printed stamps. The other two are part of the collection at the British Postal Museum.