Excluding collections, Langford's most recent professionally published book is "The End of Harry Potter?" (2006), an unauthorised companion to the famous series by J. K. Rowling. The work was published after the publication of the sixth volume in the Harry Potter series, but before publication of the seventh and final volume. It contains information, extracted from the books and from Rowling's many public statements, about the wizarding world and popular theories concerning how the plot will develop in the last book. A revised version was published in the US in March 2007 by Tor Books, and in paperback form in the UK in May 2007. The book was commissioned from Langford by Malcolm Edwards of Orion Books, who were seeking a book about the Harry Potter series.