Why is everyone trying to HIDE the wheel? All this faffing about with did ATC tell the pilots/should the cabin crew tell the pilots/should there be camera coverage of the engines belies the point that the actual evacuation was rushed by the Captain and dangerous with an engine still running. The focus should be on what have BA done to sort this out.
The dual fire bottle firing, by-the-way, is to ensure there are no highly charged explosive bottles left around for the fire crew.