<<When Heathrow tower was evacuated the aircraft were allowed to land on their own, and then find their own stand.>>
Heathrow Tower was evacuated several times when I was there; in fact I took part in the very first one!! Nothing such as you suggest happened during any of them I find it incredibly difficult to believe that this could happen. I'll just say that if it did, then the crews of the aircraft were monstrously irresponsible..