There is one item of REALLY GOOD news. This is unlikely to happen again.
The next time any carrier lands up at a LGW due fog at the other place - they will be sure to feed and water them first and then make a deceision to get them off and bus them, with their luggage to arrive later. Since a carrier rep could have been at LGW within an hour of the a/c landing to direct ops at first hand - you can be sure that will happen next time.
Yes, these folks have been VERY unfortunate but the public rumpus - yay for social networks and customers not afraid to shout in public - then this has been a wonderful lesson for everyone.
I am not joking. What they need to do now is publically apologise and send a little compensation to each pax. It's called damage limitation. This has been nasty but if we see this happen to AI again - then you will know that they ARE incompetent.