Roger is a retired antiquarian bookseller specialising in science, medicine and engineering. He worked for Bernard Quaritch and Pickering and Chatto Ltd before setting up his own business in 1989. He has helped build many private collections and has worked closely with many of the great rare book collections in the UK and the USA, including the Wellcome Library, Cambridge University Library, the Bodleian; the university libraries of Cornell, Columbia, Harvard, Princeton, UCLA, and Yale; and the Newberry, Morgan and Folger Libraries. He has taught seminars and courses on the history of scientific illustration in Oxford, Cambridge and at the Max Planck Institute for the History of Science in Berlin. He teaches regular courses for Rare Book School, University of Virginia: ‘The Illustrated Scientific Book to 1800’ in Charlottesville and ‘Six Hundred Years of Botanical Illustration’ at the Oak Spring Garden Foundation.