"Diva who became a Dame was a Nazi." Such have been the headlines prompted by a new unauthorised biography of Elisabeth Schwarzkopf, in which the author, Alan Jefferson, has had the temerity to state that the great soprano not only joined the Party but found the link professionally useful.

Yet, beyond the great lady's assertion that she has never been concerned with politics, Cathy Wearing's radio portrait of Schwarzkopf, Her Master's Voice (to be broadcast on R3 this Sunday at 5.45pm), contains not a whiff of her reported fury over the book. Or does it? In fact, Wearing had wisely left the key question until last. The reply was a half-hour tirade so virulent that any snatch of it would, says Wearing, have "completely unbalanced the programme".

"The striking thing was that throughout the interview she had constantly alluded to the consequences of her party membership. It was a stream of consciousness which - if you didn't know what she was talking about - would have made no sense. But I did know what she was talking about: she didn't want to be labelled a Nazi. She complained about 'jealous colleagues' impeding her career in America, but it wasn't that at all. It was simply people - some of whom had fled the Nazis - protesting at her wartime associations."