Big John wrote

If flight was direct from way point to way point then I doubt if
the birds came within visual range??? Would be an odd throw of
the dice.

Aircraft across the North Atlantic fly on the Organized NA Tracks.
They are similiar to airways but change every 12 hours or so
depending on winds and traffic needs.

That said, I can postulate a situation where two birds with a
few thousand feet vertical clearance going the same direction on
the same route and with different cruising speeds, slowly pass
each other and BA be able to recognize the distinctive paint job
on AF1. This in day light of course.

It was not difficult at all to recognize aircraft type and operator
when overtaking (or being overtaken) by traffic that was 2,000'
higher or lower. Used to have (1980's) some interesting
conversations with Air Force C-141 types who were "getting out"
soon about "who's hiring and what's the job like". They typically
were cruising at M.76 as we went by at M.82 in the B-707s.

Bob Moore