At the risk of making the most pedantic post of the year, I checked back in the BA timetables for 1989-1992 earlier today. Karachi was served by a TriStar routing over Kuwait (BA147/149) and stopped in Winter 1990/91 as evidently Kuwait services had stopped (not out of choice) at the same time. There was no mention of any BA 767 operation to Karachi anywhere.