Sara Mohr-Pietsch introduces a concert in which Pierre Boulez conducts two of Janacek's greatest non-theatrical works, Sinfonietta and the Glagolitic Mass, and the quirky Capriccio for piano (left hand only). Organist Simon Preston and pianist Jean-Efflam Bavouzet join the massed forces of the BBC Symphony Chorus, the London Symphony Chorus and the BBC Symphony Orchestra.