This collections contains material from the establishment of the firm to the mid-1960s. For the first thirty years most of the surviving records are of a formal nature. They include a run of eighty-seven letter-books, beginning in 1903 (before Sidgwick was in partnership with Jackson) and ending in 1941. With the legal agreements, minute-books of directors' meetings and account books, they provide a coherent picture of the workings of the firm. After the death in 1939 of Frank Sidgwick, who had been managing director since 1909, the papers, though greater in bulk, are more fragmentary, and it is therefore more difficult to piece together a clear record of the complex post-war business. Most information for this later period is contained in correspondence.

Frank Sidgwick was in partnership with A.H. Bullen (1857-1920) from 1902 to 1907, and there survives in this collection an interesting series of letters to him from Bullen, 1907-20, mainly relating to the Shakespeare Head Press. In the later period, the collection also contains files of correspondence relating to other publishers.