The Harold Isherwood Kay papers include materials relating to Kay's work. There are no family or personal papers. The archive includes 1. Notebooks recording visits to museums, galleries, art dealers, and private houses in Britain and Europe to view works of art for Kay's work at the National Gallery, valuations he undertook for the Estate Duty Office, and for his private research. 2. Research notes and drafts for his proposed book on the history of Spanish Painting. 3. Correspondence with his friend and one time colleague at the National Gallery, Ellis Waterhouse; 4. Research papers; 5. Miscellaneous items.
The archive contains some items that date from after Kay's death which may have been added by his widow or others, for example, a small file of research material and correspondence about Willem Van de Velde (both the Elder and the Younger).