So what happens to those aircraft who have creatively "committed to Heathrow" due to a shortage of fuel (on the basis that Heathrow has two runways and the weather is reasonable) when both runways suddenly shut?
Do they land at Heathrow without fire cover or do they now demand priority over everyone else who is diverting at the same time?
I would not like to be in that situation.
You could end up in deep !!!!! just because a coffee cup or an ELT has caught fire in a Boeing 787 on a remote stand at Heathrow.