BBC Proms host Katie Derham explores the remarkable provenance of the highest estimated musical manuscript ever to appear at auction. Learn what inspired Mahler from his biographer Norman Lebrecht, watch conductor Sir Mark Elder interpret Mahler’s distinctive handwriting, and discover how American businessman Gilbert Kaplan became so infatuated with the symphony he dedicated his life to learning how to conduct it. The manuscript will be sold as part of Sotheby’s bi-annual Music and Continental Books and Manuscripts sale in London on 29 November.