Penny Black print run was 286,700 sheets, containing a total of 68,808,000 stamps. Many were saved, and in used condition they remain readily available to stamp collectors. The only known complete sheets of the Penny Black are owned by the British Postal Museum. In addition to the general issue of the Penny Black, a similar stamp intended for official mail was produced, with the letters "V" and "R" replacing the crosses in the top corners. Because the general public quickly accepted the postage stamps and ridiculed the Mulready stationery produced at the same time, vast supplies of Mulready letter sheets were given
Penny Black people still reused stamps by combining the uncancelled parts of two stamps to form an unused whole, so in 1864 as a further safeguard the top corner stars on the Penny Red were replaced by the lower corner check letters in reverse order. Imprimatur sheets are from among the first sheets of stamps printed from a finished printing plate. The actual imprimatur (Let it be printed) refers to the written permission of the Inland Revenue officials entered on the back of the sheet of stamps. In the 19th century, it was common for officials to remove some stamps from each