An 800-word Harry Potter prequel is one of 13 card-sized works to be sold at a charity auction in the British capital. Waterstone's Booksellers Ltd. says the cream-colored A5 papers — each slightly bigger than a postcard — were distributed to 13 authors and illustrators, including the boy wizard's creator J.K. Rowling, Nobel Prize winner Doris Lessing, novelist Margaret Atwood and playwright Tom Stoppard.

Rowling used both sides of her card to hand-write a prequel to her seven-book Harry Potter saga, while Lessing penned a story about the power of reading. Stoppard wrote a short mystery and Atwood was due to fill out her card remotely using a robotic arm controlled by computer linkup. Other cards were completed by children's author Michael Rosen, illustrator Axel Scheffler, graphic novelist Neil Gaiman, Lisa Appignanesi, Richard Ford, Lauren Child, Irvine Welsh, Sebastian Faulks and Nick Hornby, who plastered his card with a collage.

The cards will go on sale at the "What's Your Story?" auction at Waterstone's flagship store in central London on June 10. The proceeds are to go to English PEN, the writers' association, and the British charity Dyslexia Action. Copies of the cards will be collated into a book to be made available at the bookstore and online in August.