Goodwill & Loyalty
Incidents like this go to show just how much goodwill major airlines enjoy. BA have (and in their time Swissair TWA and PANAM and others had) a mythos of quality, in which people want to believe.
These outfits can get away with murder and still people remain loyal... This has its limits if you look at the names in the brackets above.
Can you imagine what would have happened to easyJet if the same had been done at LTN? It would have finished the airline. In the case of BA it is for sure at least a nail in the coffin...