Alfredo in La traviata (1971, 1972, 1973, 1974), Don Ottavio in Don Giovanni (1972) and Sali in Frederick Delius' A Village Romeo and Juliet (1973). He later returned to the NYCO on numerous occasions in the 1980s, performing the parts of Tito in La Clemenza di Tito (1981), Pinkerton in Madama Butterfly (1983), Nanki-Poo in The Mikado (1984), Prince Karl Franz in The Student Prince (1987)., and Alfredo to Marilyn Mims' Violetta in La traviata in July 1987. His final performance with the NYCO was as Sid El Kar in Sigmund Romberg's The Desert Song in August 1987. In addition to the NYCO and SFO, Stewart has performed as a guest artist with several other America opera companies. In 1971 he made his debut with the Philadelphia Lyric Opera Company as Cassio in Verdi's Otello with Jon Vickers in the title role. In 1972 he made his debut at the Washington National Opera as Sali in the United States premiere of Frederick Delius' A Village Romeo and Juliet. In 1973 he made his debut at the Metropolitan Opera as Don Ottavio in Mozart's Don Giovanni with John Reardon in the title role and Ignace Strasfogel conducting. With the Handel Society of New York he sang the role of Oronte in the New York premiere of Handel's Alcina, which had been performed only once before in the United States, on March 25, 1974 under the baton of Brian Priestman. The performance in Carnegie Hall, with Cristina Deutekom in the title role, was recorded. Other companies he has sung with include the Cincinnati Opera, the Florentine Opera, the Fort Worth Opera, the Houston Grand Opera, the Opera Theatre of Saint Louis, the Pittsburgh Opera, the San Antonio Grand Opera Festival, and the San Diego Opera among others. Some of the other roles in his repertoire include Cavaradossi in Tosca, Ernesto in Don Pasquale, Nadir in Les pêcheurs de perles, Nemorino in L'elisir d'amore, Roberto in Maria Stuarda, Rodolfo in La bohème, and Roméo in Roméo et Juliette. In 1974 Stewart joined the roster of artists at the Frankfurt Opera in Germany. He remained a member of that company up until his retirement from the stage in 1990. During his career he also sang the concert repertoire with major orchestras like the New York Philharmonic, the Philadelphia Orchestra, and the Cleveland Symphony, among others. In 1990 he moved with his wife, stage director