How prevalent are photos for anyone else that was there at the same time? From what I can tell there is a bigger gap than just when he wasn’t there. Could be lots of reasons for that.
If all of this bothers you so bad, head up to Cambridge and really look at all of the sources. It would seem the easiest way.
Someone seems to have already tried that, it’s what this thread is all about.
And thanks for the suggestion. I’m in Australia.