The Mercury story is well known to collectors. It concerns a small American company, run by the husband-and-wife team of Robert Fine and Wilma Cozart Fine. Throughout the 1950s and 60s they produced classical recordings in the US, and later in Britain and even Russia. In orchestral music, their aim was to reproduce the sound as heard by the conductor. Initially in mono sessions that meant suspending a single microphone above the conductor’s head. The one microphone extended to three when stereo was introduced in 1956, but it was still up to the conductor – not the recording engineer – to balance the musical forces so that everything could be heard that needed to be heard.

Mercury prided itself on sonic realism (“Mercury Living Presence”), and the sound certainly was present: literally ‘in your face’. It required two things: a hall with natural ambience and good acoustics, as these aspects were not controlled by the engineer (once the optimal microphone positions were established), and a conductor who could produce a performance that was well balanced, rhythmically tight, and as vivid as the sound itself. In central repertoire, Mercury had three such conductors: Rafael Kubelík (with the Chicago Orchestra in the...