Between 1841 and 1879, British authorities issued billions of Penny Red stamps, serving a communication revolution driven by rising literacy rates that saw letter-writing boom.

Philatelists are indifferent to the hundreds of thousands of these that have survived. The Plate 77 Penny Red, however, quickens the pulse and, for the deep pocketed and extremely fortunate collector, prompts the transfer of a six-figure sum. One such specimen, labelled Britain’s “rarest and most valuable” stamp, has been put up for sale for £650,000 ($844,000).

The reason for Plate 77 Penny Red’s legendary status is that it shouldn’t exist. A single sheet of 240 stamps was printed in 1864 before authorities realized the plate was faulty—poor alignment caused the stamps to be mis-perforated. The plate and the sheet were promptly destroyed, but somehow, nine stamps escaped, one of which is believed lost to the 1906 San Francisco earthquake.

Of the remaining stamps, three are in private hands with the rest in museum collections, including the British Library and the Royal Philatelic Collection (nice one, King George V).

The stamp was discovered by a Manchester dealer in the 1920s with the current seller, Paul Fraser Collectibles, stating that it “has graced some of the finest stamp collections ever formed.”

The stamp featuring Queen Victoria’s profile is marked with a small “77” to denote the plate number and “PI” to identify its place on the plate. The stamp appears on its original envelope and alongside a four-penny stamp. The postmark on top of the stamps shows they were used in Highbury, London, and have been canceled.

It was last sold in 2012 for £550,000 (roughly $1 million today).

“While most people know the Penny Black was the first stamp,” said Mike Hall of Paul Fraser Collectibles, “it’s plate 77 Penny Reds that send collectors into a frenzy.”

The Penny Red replaced the short-lived Penny Black, the world’s first adhesive postage stamp to be used in a public postage system. The Penny Black was replaced after it was found that the red cancellation could be scrubbed off, allowing it to be reused. Authorities chose to swap the colors, issuing a red stamp with a black cancellation, as shown in this example Penny Red 77.

Despite the lofty price, it’s far from the highest paid by philatelists. In 2014, $12.2 million was paid for the British Guiana 1c magenta; in 2021, this was trumped by the sale of an envelope bearing a Mauritius Post Office 1d red for $12.6 million.