The Variorum Gilbert & Sullivan, Volume I, is the essential textual reference to the first four operas by W. S. Gilbert and Arthur Sullivan: Thespis, Trial by Jury, The Sorcerer, and H. M. S. Pinafore. The editors, Marc Shepherd and Michael Walters, have researched hundreds of sources, including early drafts never before published). Shepherd and Walters present a detailed history of the text of each opera, including: pre-production drafts, manuscripts, early libretti and scores, and prompt books, through revivals, twentieth-century DÕOyly Carte amendments, and the contributions of later editors and editions.