Suzy Klein introduces two works concerned with death. Britten's Sinfonia da Requiem was commissioned for the 2,600th anniversary of the Japanese Imperial Dynasty but was turned into a requiem for his recently-deceased parents, and Mahler's painfully expressive farewell to life, his 10th Symphony, left unfinished at his death but completed by Derek Cooke. Gianandrea Noseda conducts the BBC Philharmonic.