This can't be good. According to a Guardian article the British Library is missing over 9,000 books, including Renaissance treatises on theology, a medieval text on astronomy, and a first edition of Oscar Wilde's only novel, The Picture of Dorian Gray, published in 1891. That has missing from the library's shelves since 1961. A special edition of Mein Kampf produced in 1939 to celebrate Hitler's 50th birthday is also unaccounted for.
The library believes that most of the items are not stolen but rather mishelved among its 650 kilometers of shelves and 150 million items. Some items have not been seen in well over half a century.
The library records all of these items as "mislaid" rather than missing or stolen. Jennifer Perkins, the library's head of records, said that books and other items were usually identified as mislaid when a reader requested them. Other losses were revealed in rolling audits of the enormous collection.
The British Library also houses the Magna Carta. This and other special collections are kept in a special gallery with security controls. The rest of the collection is identified by barcodes and shelf numbers not by microchips. Many of the losses are recorded just before or after 1998, the year the library moved from the British Museum to Saint Pancras. Most of the losses are 19th and 20th century texts, including first editions of novels by Charles Dickens and John Updike, although many older books have also vanished as well.