SWBKCB
I'm looking at this from the customers point of view, and it looks like BA take the easy option and just shut down domestic operations rather than make the effort and try to offer some sort of service to those who pay the wages.
As much as I find irritating about BA mgmt, I work on the presumption that they don't like to canx flights. It makes their day longer and noiser and more stressfull. They will have been through this many times and know what can be done and what cannot. The facts of what has happened and what will happen the next time there is bad fog at ANY airport ANYWHERE in the world are well known.
mmeteesside
How about moving whatever's left of the long haul fleet across to LGW, and starting operating B744's or B772's on the domestic routes from there? Move the pax across to LGW on coaches and soon you'll have them all out of your way.
Do-able or not?
No. How do you communicate to ALL your passengers to go to a different ariport? You might get 50% but if even 10% don't get the message and cannot get to the alternative departure point - they will be as upset as if you had canx the flight.
More critically, each ferry movement of an empty machine out of EGLL and across to EGKK is two more slots removed from a system that is already (wait for it) slot limited! Not to mention that it costs hard cash in fees and fuel and diminishes the hours of the crews who may already have to spend much time waiting - to send them on a ferry flight and use more time and money does not work. That kind of action would be reserved for a long term event - let us say that T1 was out of action due to a very bad fire.