In volume one of the two-volume first edition of Our Mutual Friend, this separate slip of paper was inserted, stating “The Reader will understand the use of the popular phrase Our Mutual Friend, as the title of this book, on arriving at the Ninth Chapter (page 84).”  The slip is cited by Eckel as part of the proper collation of the first edition.  The slip is clearly intended to interest the reader in the identity of the “Mutual Friend”, who is revealed on page 84 to be Mr. Rokesmith.