Having previously sung Bach’s Mass in B minor, which is packed with magnificent choruses, I was initially a little surprised by how little the choir seemed to have to do in the St Matthew Passion. There are, of course, the two great choruses that open and close the work – Kommt, ihr Töchter... and Wir setzen uns..., the latter being, for me, one of the greatest pieces in all classical music. But much of the remaining choral writing consists of short, sometimes rather bitty interjections, interspersed with numerous chorales, several based on the familiar melody of O Haupt voll Blut und Wunden.

Gradually, though, you realise that singing the St Matthew Passion is a bit like taking part in an opera. The choir becomes part of the drama, including playing the crowds who witness, question, mock and ultimately condemn Jesus. It becomes much more than simply singing a succession of choruses – you're helping to tell the story.

The work is also unusual in being written for two choirs, each with its own accompaniment. The two often exchange phrases in a kind of musical dialogue, while other movements are assigned to one choir or the other. Consequently, you don't even sing all the choral music yourself, but listening to the other choir is very much part of the experience.

And these short choruses can be incredibly powerful. Perhaps none more so than the two cries of Lass ihn kreuzigen! (‘Let him be crucified!’), where Bach uses harsh, dissonant harmonies to capture the horror of the crowd's demands.