Excestre, William, English singer and composer who flourished c. 1390–1410. He was clerk of the Chapel Royal in 1393, and received a prebend in St. Stephen’s, Westminster, in 1394. He was one of the composers whose music is contained in the Old Hall Manuscript. A Gloria, a Credo, and a Sanctus (all for 3 Voices) are extant.
—Nicolas Slonimsky/Laura Kuhn/Dennis McIntire