“You are the greatest Brünnhilde I have heard in 40 years.”

“And who did you hear 40 years ago?” inquired Birgit Nilsson of what must have been a momentarily flummoxed Karl Böhm.

The wit and the voice seem utterly inseparable to us now – disarming, unflagging and totally at the legendary soprano’s beck and call. It could lash, or it could draw you in closer: it could certainly do both at the same time. With the advent of the centenary of her birth, the image of the laughing Valkyrie burns brighter than ever. There she jokes about Rudolf Bing being a dependent. Here she accuses a competitive Franco Corelli of giving her rabies. There she identifies her imitation pearls as bought with the meagre fees of the Vienna Opera.

Birgit Nilsson. Photo © Siegfried Lauterwasser/DG 

We hear the same stories over and again, some undoubtedly apocryphal. But the spark of a quick mind and the brilliance of a steely attitude makes them evergreen. Akin to putting on one of her records, it makes you wonder – how could this woman, with such outsized, positively Wagnerian qualities, ever possibly...