While it would be difficult to confuse him with a countertenor, Elwes' exceptionally high-lying and secure upper register have enabled him to sing some of the most demanding repertoire, including Rameau pieces that are seldom performed today because of the difficulty in casting the tenor leads. Born John Hahessy, Elwes sang in the Westminster Cathedral choir, where he also studied music under George Malcolm and eventually became head chorister. He also had an extended career as a boy soprano, including singing Isaac in the world premiere recording of Britten's canticle Abraham and Isaac. (Britten greatly admired his work and dedicated his Corpus Christi Carol to him.) When he was still a teenager, he lived with the family of tenor George Elwes, and in gratitude for their support, he changed his name as a tribute to Elwes. After continuing his music studies at the Royal College of Music, he made his stage debut as a tenor in 1968 at the London Proms and later performed and recorded with several early music ensembles, including the Medieval Ensemble of London and the Consort of Musicke. He has also appeared extensively in opera, where he specializes in Baroque and early Classical music, though with occasional appearances in twentieth century works by such composers as Honegger and Vaughan Williams.