The inclusion of J K Rowling's short story about Harry Potter's father and Sirius Black in a postcard collection called What's Your Story? is sending the book flying off the shelf. The story was available online a while ago on the Waterstones site but though the official version is not now viewable, you can still read the story and see the original writing on this unknowable wiki page.
Read more about the What's Your Story? collection on the Waterstones website.