What a really great post, thanks for taking the time and effort to enlighten us all.

As I had experience of last Sunday's weather-related shenanigans at LHR, it does lead me to a question:

How much interaction is there between ATC and the airlines regarding the available inbound and outbound slots in a heavy fog situation, and who is responsible for the negotiation on the individual slots available, given the reduction in arrivals and departures?