Clark studied at Kirkham Grammar School - where he was Captain of School - Loughborough College of Education and Loughborough University. After a few years as a PE teacher, followed by postgraduate studies and then as a Senior Regional Officer of the Sports Council, he took up singing. His big break came when he was selected by Richard Bonynge to appear in a charity gala at The Royal Opera House, Covent Garden on 25 January 1975 with Joan Sutherland, Heather Begg, Clifford Grant and others in aid of the Australian city of Darwin, recently devastated by Cyclone Tracy. The concert was televised and issued on LP by Decca as 'Darwin: Song for a City'. In 1975 he joined Scottish Opera, was a Principal with English National Opera from 1977 to 1985 and has had an extensive international career from 1976 to 2014. He has been nominated three times for Outstanding Individual Achievement in Opera Awards, including an Emmy and won the Olivier Award for Outstanding Achievement in Opera in 1986 for his role as Mephistopheles in Doktor Faust. He was awarded an Honorary Doctor of Letters by Loughborough University in 1999.