The Library faces west towards the garden and is larger than the Breakfast Room which faces east towards the front. The elevation/section (drawing 206) shows bookcases in both rooms with two doors (to Drawing Room and Vestibule) in the Library and two doors (one a cupboard) in the Breakfast Room. While the basic plan is the same in both drawings, the fitted furniture of bookcases is different.

The Library perspective corresponds with the plans of drawings 206 and 207, but the north wall (of the elevational section) has another arrangment of bookcases. The plaster ceiling is a shallow cross-vault ceiling.

The Library and Breakfast Room both held important pieces from Soane's collection, many bought specifically for Pitzhanger, including urns and vases, which seem to be indicated particularly in drawing 206 (even if the purchased articles are not specifically shown, the concept was clearly in Soane's mind at this time).