@LindbergB767:
I wasn't implying that it was a sane thing to do, in fact quite the opposite. At the time I didn't think much of it, other than it was very cool to be sitting in the pointy end of a 707, but thinking of it later on it did seem like insanity. On the other hand, it was by no means the only time that I was in the cockpit of an airliner in flight as a kid - times were different in many different ways.
And had we lost an engine or other indicent - well... That would have been a different story entirely. However, I can't believe that all three crew left the cockpit on the basis that there was at least one warm body in there (myself) as opposed to having left the cockpit with nobody in there. Would that have been entirely insane and irresponsible - yes, absolutely. Do I believe that it might have happened - absolutely. Did I fly with the same carrier again? Several times, but not necessarily by choice.