In the 1960s he worked at Sadler's Wells Opera and with the London Symphony Orchestra. He was Chief Conductor of the BBC Symphony Orchestra. In 1971 he took over from Georg Solti as principal conductor at the Royal Opera House. He stayed there until 1986. He particularly liked conducting the operas of Michael Tippett, giving the first performances of "The Knot Garden" (1970), and "The Ice Break" (1977). In 1977 he became the first English conductor to appear at the Bayreuth Festival where he conducted "Tannhäuser".