My brother and his wife were on this flight,he is an airline Captain & told me the evacuation was a complete shambles from beginning to end.(Obviously those congratulating themselves on a job well done are BA people).BA need to look very carefully at this incident and learn some hard lessons.Things were not helped by the poor behaviour of many passengers who insisted on taking everthing but the kitchen sink down the slides with them,one passenger threw his large case down the slide which hit a preceding passenger in the back injuring him.Ten minutes after evacuation announced pax still evacuating!Hardly a job well done.
I don't meam to completely dispute the above, but just to add another view.
It's impossible for the Cabin Crew to control an orderly evacuation. The most they can do is to provide the means by which the passengers can evacuate within a minimum time frame. Some passengers use this means while others don't. So there is the good and the room for lessons learned by the crew (I doubt that the next group of evacuating passengers will have learned anything new)
It makes me think of the Titanic movie where one of the ship officers fires a pistol over the heads of the more non complying passengers