I don't think BA has any 747 services from Gatwick.
I would sooner fly on an old BA 747 any day rather on a fifth hand old 737-300 on Jet2. I flew from Vancouver on a BA 747 which was taken out of service the next day. I felt sorry for the old girl, she seemed pretty good to me!!!
I can understand passengers getting frightened when they don't know what is happening. It is a disgrace that the tannoy was not working or even the megaphone, it just shows what the maintenance is like.
It is the same thing at airports when there is a delay, if only people were told the truth they wouldn't get so frustrated.