Canadian author Margaret Atwood plans to pen her submission to the What's Your Story? charity auction with the robotic LongPen she has developed.Canadian author Margaret Atwood plans to pen her submission to the What's Your Story? charity auction with the robotic LongPen she has developed. (Aaron Harris/Canadian Press)

Canadian award-winning novelist Margaret Atwood joins Harry Potter creator J.K. Rowling and 11 other writers whose card-sized works will be sold at a charity auction in London next month.

The signed, handwritten cards, each slightly bigger than a postcard at 14.6 cm by 20.9 cm, will be sold at the What's Your Story? charity auction at Waterstone's Booksellers Ltd.'s flagship store in Piccadilly June 10.

The auction's organizers hope the Rowling submission, an 800-word prequel to the seven-book Potter series that reveals what happened to Harry before he went to Hogwarts, will attract high bids.

"Given the enormous interest for autograph work by J.K. Rowling, there's no telling how high the bidding may go," Philip Errington, a specialist at Sotheby's auction house who is organizing the auction, told the Associated Press.

British author J.K. Rowling's 800-word prequel to her Harry Potter series will be sold at auction in London on June 10.British author J.K. Rowling's 800-word prequel to her Harry Potter series will be sold at auction in London on June 10. (Matt Dunham/Associated Press)

Last December, Rowling sold a handwritten leather-bound book of fairy tales at auction for nearly $4 million US.

She has said she has no plans for another Potter novel, and signs off her card with: "From the prequel I am not working on — but that was fun!"

Atwood, a companion of the Order of Canada and winner of the Giller Prize, the Booker Prize and the Governor General's Award, plans to fill out her card remotely using the robotic LongPen she has developed that is controlled by computer linkup.

Other contributing authors include British Nobel Prize-winning novelist Doris Lessing, British playwright Tom Stoppard, who is writing a mystery on his card, and Sebastian Faulks, British author of the new James Bond book, Devil May Care.

Proceeds from the auction will go to English PEN, the writers' association, and the British charity Dyslexia Action.

The cards will be collated into a book, which will be available at Waterstone's and online in August.

With files from the Associated Press