This recital of Austro-German repertoire (albeit composed to Italian and English texts) was prompted by Maria Callas’s indignation on discovering that her EMI producer, Walter Legge, had chosen his wife, Elisabeth Schwarzkopf, for a recording of the Verdi Requiem. ‘If your wife can sing my repertoire, then I can sing hers,’ declared Callas.

As it turned out, she complemented arias from ‘Schwarzkopf roles’ (Donna Elvira and Countess Almaviva) with one of Donna Anna’s arias and with scenas by Beethoven and Weber that she had first learned as a student in Athens (she had sung Leonore in Fidelio in Greece at the age of just 21).

‘The disc shows the voice in the excitingly fresh condition that was heard in the Covent Garden Toscas [1964]’, wrote Gramophone. ‘The Callas personality is here at its most intense. This tigress is fiercer than ever, in some ways more exciting than ever. The flashing eyes seem to drill into one, and the scalp tingles … This is an exciting disc to fire and excite admirers.’