The late Swedish soprano Birgit Nilsson (pictured) left a rich secret when she died in 2005 – her choice for the first winner of her million dollar music prize, tenor Placido Domingo.

Birgit Nilsson, whose prodigious voice, unrivalled stamina and thrilling high notes made her the greatest Wagnerian soprano of the post-Second World War era, has died. She was 87.