An insert in August's Gramophone lists comments from James Galway and
concertmaster Thomas Brandis on their experiences with Karajan.

JG:  "He started to do the slow movement (of Mozart's Flute/Harp Concerto)
but..it was totally the wrong speed, which meant he had never heard a
recording of it, and he hadn't looked at the score before."

TB: "Except for some modern pieces he didn't particularly like, he knew
all his scores by memory. His memory was immense."

Could both be right?
Tim Hu