In this day and age of instant news, it is interesting that no info on the fire is available. But it is Heathrow and not boston. The Heathrow fire deptmnt knows where the fire occurred and probably how it originated. But the news is absent of such detail. In the absence of news speculation abounds. It is in the best interest of the British and American investigative agencies to bring details to the public rapidly. But that appears to be not forthcoming. Why do we allow that to happen?
If there was any indication that passenger safety was being compromised, they would stop all world wide flights. Obviously they will take time before they declare "all clear or not " from modification perspective. Besides they may be considering sabotage, in which case they wont reveal their cards.