Grimmrad
Witnesses to any major incident will invariably have different opinions and testimony to what happened.
To give you an example... during a training course that I ran a while ago, in the middle of the class we arranged for two armed assailants to enter the class and snatch a course member, taking them "hostage" outside.
The operation from start to finish took less than twenty seconds.
With 29 people still left in the class, I asked for each one to give me a detailed written description of what they saw - paying particular attention to what the "kidnappers" said and what they wore.
The results were wide and varied - just like the descriptions of those involved in the Heathrow event.
I hope that this answers your question.