I also think tomorrow morning particularly Ryanair’s first wave of departures will be cancelled due to tonight’s last wave of inbound being stuck at out stations and some having diverteded to other UK airports not a very good Easter weekend at all.
Having said that I do not blame MAG/Stansted for the situation I bet it was quite a worrying situation have a fire on a bus not knowing the cause I think evacuating through security was the only option.