When Herbert von Karajan died on July 16, 1989, the classical record industry died a little too. Gone was a musician who had the power that could ensure that classical music stayed on the radar, who guaranteed that classical record sales could rival those of pop and rock music, and, above all, gone was someone who fascinated the musical public with the aura he’d built up over a lifetime. He had become one of the great brands of the second half of the 20th century and his absence was felt very quickly.

Karajan, who was born and died in Salzburg, the city of Mozart, continues to divide opinion – and those divisions are as much personal as musical. For the naysayers, it is Karajan the egotist, Karajan the power-crazed, even Karajan the Nazi. To the musicians who worked with him, there was a very different Karajan, a shy man, a man of humanity, and of great personal generosity, and a man who took classical music to the four corners of the globe. To the wider music-loving audience today he remains an iconic figure, the quintessential maestro, undoubtedly vain, who combined the mystique of the podium with...