Douglas James William Kinnaird (1788-1830) was an intimate friend of Lord Byron. Kinnaird was banker for the poet and after Byron went into self-imposed exile in 1816, Kinnaird also acted as his power of attorney in Britain. As a result, there are hundreds of letters between the two, as well as letters of Kinnaird to John Murray II and John Cam Hobhouse. The correspondence covers personal affairs, business matters and conversation about the works of Byron. Kinnaird was heavily involved in the publication process of the works of Byron, especially after Byron went abroad, and the correspondence here reflects this involvement. Later copies of the letters of Byron to Kinnaird are also included in this series.

There are also personal copybooks of letters of Kinnaird. These contain copies of letters of Douglas Kinnaird to a variety of correspondents.