A rare complete copy of the First Folio of William Shakespeare's plays has sold for £2.8m at a Sotheby's auction.
The First Folio contains 18 plays that had never been printed before
The book, one of about 40 complete copies known to exist, was bought by an anonymous London book dealer.
The auctioneer hailed the book, containing 36 plays, as "the most important book in English literature".
The book, still in its 17th-Century binding, includes 36 plays, 18 of which were published for the first time, including Macbeth and Twelfth Night.
"This was a spectacular auction at Sotheby's. Sales like this are few and far between," said Charles Dupplin, book sales expert at specialist insurers Hiscox.
"It is fair to say that a first edition of Shakespeare's plays would be the jewel in any book collection in the world. The one sold has achieved the highest prices ever paid at auction in the UK," he added.
"Our figures show that prices for collectible books have more than doubled in the last 10 years. It has come as no surprise that this sale has shown that the market for such material is very strong."
The book was sold by Dr Williams's Library in London to secure the library's future.
The trustees of the library believe the sale will help it conserve its historic collections.
Library director Dr David Wykes said: "The library has been proud to own this remarkable copy of Shakespeare's First Folio, but its sale will secure the finances of the library and safeguard our important historic collections of manuscripts and printed books for future generations."
The book was sold as part of Sotheby's sale of English Literature and History in London on Thursday.
It was published seven years after Shakespeare died in 1616, aged 52.
Sotheby's English literature specialist Peter Selley said: "The First Folio preserves 18 of his plays, including some of the most major, which otherwise would have been lost for all time.
"Relatively complete copies of the Folio in contemporary or near-contemporary bindings very rarely come to the market. There is only one copy recorded as remaining in private hands."
The auctioneers added that the price when new was probably 20 shillings. Some 750 copies were printed and around a third survive, which are mostly incomplete.
The First Folio contains "extensive markings and annotations" that give an "invaluable insight into its early readership", Sotheby's added.