My first visit was on a VC-10 as a newly signed member of the BOAC Junior Jet Club. December 1965 and the very first flight of my life, LHR-JNB, via CIA + NBO. I know that my siblings and I visited the flight deck but do not remember any detail - the whole event was just so exciting. I was nine years old.
The second was a Cessna 172 in January 1967 at Grand Central Airport, outside JNB as we were then living in Pretoria. It was a local air-tour for my siblings and I.
The third would have been a VC-10 Super, JNB-LHR (via NBO) on a daylight flight in June 1971. They were very much 'old school' flight decks with Flt Eng, Nav and fabulous dials and levers!
I shall have to think carefully as to which was the next visit.