The St Matthew Passion is one of the greatest pieces of music ever written. But what was it like to play and sing and hear it for the first time? James Runcie, author of The Grantchester Mysteries, talks about the imaginative research involved in writing his new novel The Great Passion, the story behind the composition, rehearsal and first performance of Bach’s masterpiece in April 1727. This event is interspersed with Bach’s D minor partita performed by brilliant young French violinist Irène Duval.