June 10 (Bloomberg) -- J.K. Rowling's handwritten prequel to the ``Harry Potter'' novels fetched 25,000 pounds ($48,855) at a charity auction in London tonight.

The signed, 800-word tale was one of 13 ``storycards'' written on sheets of A5 paper being offered by Waterstone's, a U.K. bookseller. The signed piece concludes with the teasing words ``from the prequel I am not working on -- but that was fun!''

The buyer was an absentee bidder. More than 100 guests attended the invitation-only event, called ``What's Your Story?'' and run by Sotheby's auctioneer Edward Rising at the Waterstone's branch in Piccadilly.

Rowling, 42, has ruled out a full prequel to the novels about the boy wizard, which have sold about 400 million copies. Other works were being sold by authors including Sebastian Faulks, Richard Ford, Doris Lessing, Nick Hornby and Tom Stoppard. Proceeds go to English PEN and Dyslexia Action, said Waterstone's, which is owned by HMV Group Plc.

In December 2007 at a Sotheby's London charity sale, Amazon.com Inc. paid a record auction price of 1.95 million pounds ($3.98 million) for Rowling's handwritten volume of fairy tales, ``The Tales of Beedle the Bard.''

(Scott Reyburn writes about the art market for Bloomberg News. Any opinions expressed are his own.)

To contact the reporter on this story: Scott Reyburn in London at sreyburn@hotmail.com.

Last Updated: June 10, 2008 15:55 EDT