This series contains original letters to Barker and typescript carbon copies or photocopies of letters from him. Much of the correspondence is with authors and prospective authors. A few letters relate to Barker's investment in the Collector Ltd. Interfiled with Barker's correspondence are some letters to and from others on the editorial staff, including David McKitterick, John Commander, and chiefly Joan Stevenson (1966-ca. 1979). Some letters to and from her include proofs of articles.

Chiefly original letters to Hayward and typescript carbon copies of letters from him. Some other letters forwarded or copied to him are also included. Some letters here relate to articles not published. A small number are unrelated to the Book Collector at all. A few other papers of Hayward's, not correspondence, are in items 78 and 80. Hayward's correspondence with advertisers is generally in series E.

Includes letters from Ashley Sampson (1946), Reg Scott (1966), W. A. Shepherd (1973), J. S. G. Simmons (1972), R. Smith (1959) Stephenson Blake (James Blake, 1968), James Sutton (1968), and E. Sykes (1958).