Schwarz received praise from Thomas Beecham as an "able conductor" for his work with the Bournemouth orchestra, and subsequently held Principal Conductor positions with the City of Birmingham Symphony Orchestra (1951–1957) and the BBC Symphony Orchestra. With the BBC SO, he was praised for his efforts "to reach the truth of the music". However, in the 1961-1962 season his interpretation of Mahler's Symphony No. 9 was criticised in the press as "blatant misrepresentation", and as moving "from bad to worse". In addition to press criticism, Schwarz contended with the appointment in 1959 of William Glock as Director of Music at the BBC. Conflict between Glock and Schwarz over such matters as style and repertoire may have contributed to the conductor's departure from the organisation in 1962. Additionally in March 1962, Schwarz conducted the BBC SO at the Royal Festival Hall, in Jacqueline du Pré's concerto début of Elgar's Cello Concerto.