Great illustrations Richard. What computer technology you have at your fingertips!
In reply to David, please be assured that there WAS a landing on that evening at after 11.15pm (Southern Runway)and also a take off soon afterwards too. The northern runway activity we have already discuss.
I really do have a bird's eye view of a great deal of Heathrow activity...and after 11pm noise doesn't always go unnoticed..especially when the drone of the M4 has gone to bed for the night..until 5am!
So those tracking websites must miss some of the happenings!