Elsewhere, he became the Australian Opera's Music Director in 1970, conducting the first operatic performance in the Sydney Opera House in 1973, the Australian premiere of "War and Peace" by Sergei Prokofiev. He was Chief Conductor of the Netherlands Radio Orchestra until 1983. While Downes worked with many of the world's symphony orchestras, he enjoyed a particularly long relationship with the BBC Philharmonic (formerly the BBC Northern Symphony Orchestra), serving as its Chief Guest Conductor, then Principal Conductor, and finally as Conductor Emeritus.