These rehearsal sequences give a vivid idea of Sir Georg Solti’s approach in his mid-fifties as he was emerging as one of the world’s leading conductors. Though his reputation at that time – at least with British orchestral players – was one of impatience and even irascibility, it is the opposite here. Maybe influenced by knowing the cameras were on him, he talks more than one might expect, and the vast majority of his instructions involve subtle gradations; he’s concerned not with the brilliant, extrovert qualities one might have expected, but with the shading of pianissimi and moulding of legato phrases.

So in the Tannhäuser Overture he spends almost all of the 45 minutes of the first rehearsal sequence getting the slow introduction as he wants it, notably the hushed opening on the horns, then letting the players off the rein with a cry of release when the great trombone theme enters. He quotes, when the relevant theme arrives, the words of Tannhäuser in the opera, that the burden of his sins is weighing him down. The fast sections he tends to leave alone in his instructions, relying on fierce information from his baton.

The Berlioz similarly finds Solti concentrating on refined points, and charmingly he goes into some detail about how Berlioz was given the theme by Liszt, and was instantly magnetised. It is, Solti explains, an old Hungarian song of liberation, a joyful march associated with Rakóczy as a freedom fighter. That leader failed, but, then, says Solti with a grin, Hungarians always fail.

The big limitation is that the rehearsal sequences are conducted in German. Though you have the option of subtitles in English, the translation involved inevitably dilutes the experience; the English is designed for an American audience: semiquavers become 16th-notes and crotchets quarter-notes – though that, of course, is a direct translation of the German.

The performances are as polished and refined as the rehearsals promise. Solti complains at the beginning of his first rehearsal about the unhelpful acoustic – ‘a bit harsh for my taste’ – but promises to compensate. He certainly does.