Every so often the Discworld Emporium entertains us collectors with one of their infamous cock-ups. This stamp is associated with the original cock-up. A sub-story within Going Postal has Moist von Lipwig trying to prove that a mail service is both cheap and reliable. To do this he personally takes a letter from the Post Office to Sto Lat by horseback, and returns within the day not only with a reply, but a collection of mail to be delivered to friends and relatives in Ankh Morpork. The letter he takes, according to the book, bears 5 red stamps to the value of 10 pence. Hence the Ride To Sto Lat letter, of which 250 were produced to commemorate this event. What went wrong? 500 red versions of the 10p Morpokia design were printed. These were subsequently given to collectors as the free gift in issue 4 of the Journal. The correct stamps were then printed and the Two-penny Red was born. The covers were available to collectors as the special offer with Journal issue 3.

A few single stamps also found their way into some Dragon Sanctuary envelopes. The stamp is similar to the one penny stamp with cabbages in the top cartouches. No sports of this stamp have been reported .... yet.
If you are wondering what the letter contained, all is revealed here.