I thought you might be interested in a few pictures taken on 22 January 1976: the concert at the Volkshaus in Zurich was the second time I saw Procol Harum live.
I remember very well Gary mentioning this during his introduction of The Unquiet Zone (featuring Mick's guitar) and the audience joining the other band members on Happy Birthday.
By the way, don't be confused by the fact that some band members appear in two different clothes. The photos were still shot at the same time and place - the dresses were changed during intermission.
Thanks, Ernst … who acquired the pictures in the 1970s, not knowing that they had been taken by photographer Ueli Frey