The Nobile Index is a series of monographic publications of art sales prices achieved at auction, for a selection of leading 20th-century British artists - Walter Sickert, David Bomberg, L.S. Lowry, Stanley Spencer and Francis Bacon & Lucien Freud. They involve the collaboration of a commercial art dealership, Piano Nobile Works of Art and the University of Bristol's History of Art Department; bringing together academic and commercial expertise on the artists for the benefit of those with an interest in their work. They are funded by the generosity of a private benefactor. The studies are confined to analyses of auction art sales results from 1990 to the time of the study. Although largely from UK sales, data supplied by international salerooms are also included. Graphs and interpretations of these figures are analysed and significant trends and buying patterns revealed. It is envisaged that this data will be of growing value to private and corporate clients, museums and fine art funds. Accurate commercial appraisal has always played an important role in the consideration of new acquisitions throughout the history of art. No more so than today is this seen with the fluctuating, but ever more significant rise in value commanded by the best of many 20th-century artists' work.