Fume Event should already know that BA have received approval from the CAA for the new crewing arrangements. The name of the CAA contact who confirmed this is available on the dark side forum. The regulator has concluded that if the crew are standing in the aisles doing the safety demo (which is when door 5 is unguarded) then they should be able to get to the door in an emergency faster than seated and strapped in passengers. Of course it doesn't help if you're trying to play the safety card and the regulator has stated that there isn't a card to be played.