There are approximately 425 original drawings by Bowles in the Lindley Library Art Collection, some of which were removed from among his papers in the 1950s and transferred to the Art Collection. They are catalogued as drawings and can be searched on the Library catalogue. Drawings include original pencil drawings for a monograph on Narcissus, watercolour drawings of Galanthus bound in one volume by the Library, and miscellaneous plant portraits, garden views, people portraits, still life including birds, and holiday scenes
Many drawings and sketches remain among Bowles' papers in the archive. These are catalogued as archives, using the term 'drawing', and can be searched on the archive catalogue
Bowles created silhouette representations of himself, his friends and acquaintances. These may be found in EAB/7/1, EAB/7/3 and EAB/7/4