Duncan studied at the Royal College of Music and, subsequently, at the age of twenty-three, was offered the position of Trainee Répétiteur at English National Opera under the tutelage of Sir Mark Elder.

He then became a full-time member of the music staff of Opera North and again at English National Opera. Since 1997 he has been working freelance for many of the major international festivals including Salzburg and Glyndebourne. Duncan has had a close relationship with the latter, where he specialises in 19th and 20th Century German and Czech repertoire.

Whilst at Glyndebourne, Duncan performed regularly as an actor too: Lutheran priest in Die Meistersinger von Nürnberg, a piano-playing champagne bottle in Die Fledermausand and an irate member of a circus troupe in The Bartered Bride! He particularly enjoys his work at Scottish Opera, where most memorable productions include Wagner’s Ring Cycle and Strauss’s Der Rosenkavalier.

He is often called upon as a recital pianist and has performed with great singers such as a Gerald Finley and Danielle Denise among many. He has worked for Chandos and Deutsche Grammophon, and performed with the London Philharmonic Orchestra, Philharmonia, and Scottish Chamber Orchestra.

He has collaborated with numerous internationally renowned conductors including Sir Simon Rattle, Sir Mark Elder, Robin Ticciati, Kazushi Ono, Jirí Belohlávek, Sir Charles Mackerras, Vladimir Jurowski, and Andris Nelsons. Duncan has had a relationship with the Royal Conservatoire of Scotland for the last 20 years as both teacher and visiting coach, and has now taken up the post of full-time coach in the Opera Department.