Letters received by the Opies from the general public in reply to their letters to the editor asking for information on nursery rhymes and childlore, and professional correspondence with researchers, academics, authors, booksellers, collectors, cultural and heritage institutions, the media, and other contacts and enquirers. Also includes general correspondence with the Opies’ publisher Clarendon Press, later Oxford University Press (for correspondence relating to specific publications, see C. Publications). The extensive correspondence with Doreen Gullen, the Opies’ long-term research collaborator and friend, covers both professional and private topics.

The Opies’ address books, which link each correspondent to a reference number and often give background details on their correspondents and their activities, can be found in MS. Opie 215.