British composer (1842–1900) best known for his collaborations on more than a dozen classic comic operas with librettist W. S. Gilbert. ALS, one page, 5 x 7, April 1, 1870. Sullivan writes to Mr. Martin. In full: “Pray accept my best thanks for your cheque, and the very kind note accompanying it.” In very good condition, with letter mounted to a larger album page (faint glue stains and wrinkles), marginal rust stain, and a few edge tears. R&R COA.