Before the issuance of the Penny Black—the first adhesive stamp to indicate prepayment of postage—letters were commonly paid for by their recipients. Part of an effort to reform the antiquated British postal system, the stamp featured a profile of Queen Victoria. Because its dark background made cancellation marks hard to see and made reusing stamps quite easy, it was soon redesigned. To this day, all British stamps bear a profile of the reigning monarch and are the only stamps not to list what? Discuss
Source: The Free Dictionary