In this 35th episode of Merely Catholic, the podcast series for The Catholic Herald, Dr Gavin Ashenden talks to Simon Johnson, the Master of Music at Westminster Cathedral and a man described as “one of the most versatile musicians of his generation”.

Mr Johnson is a virtuoso organist with extensive work in choral direction, composition and arrangement and for 13 years he also served as the Organist and Assistant Director of Music at St Paul's Cathedral.

Together they explore what liturgical music is and what it does ahead of preparations by the world-famous Westminster Cathedral Choir and Orchester, for which Mr Johnson is responsible, for a mesmerising performance of St John Passion by J.S. Bach in the cathedral on Thursday March 16.