The last time a BA 777 needed to send the pax down the slides was at LHR a few years back; icing in the heat exchanger of the Rolls Royce engines at a very critical moment on approach.
This time General Electric engines, apparently an older type that has been modified according to B-HKD, posted at 0.249 Sept. 9 on this thread. Some contributors have suggested if the takeoff had been continued the engine fire may have been more easily contained. And as engine fires do happen now and then, will this one be investigated as thoroughly as the RR problem?