1968/9? The most memorable concert (perhaps I was more easily pleased at age 16/17) was Georg Szell conducting the Eroica Symphony with Sir Clifford Curzon playing a Mozart concerto in the first half (was it D Minor, C Minor or A Minor K488?, one of my favourites anyway.)  I also remember late 60s Karl Richter conducting St John Passion with Ernst Haffliger as evangelist and a large orchestra.  Richter directed from the harpsicord.  Saddest was Britten's memorial concert (1976).