The Puzzle

The famous ‘Penny Black', the world's first postage stamp, was introduced in England in 1840. The idea of postage stamps was a great success and was taken up worldwide. Yet the ‘Penny Black' was in use for only one year before it was replaced by the ‘Penny Red'. Why?
[learn_more caption=”Solution”]The postmark used at that time was always black. It was therefore difficult to tell whether a stamp had been franked or not. This led to people re-using used stamps. On a ‘Penny Red' the black postmark was clearly visible. [/learn_more]