Could also have something to do with short haul rostering agreements and the minimum turnaround times required by cabin crew in particular at LHR which means that the aircraft, pilots and cabin crew are normally rostered separately, so when inbound flights are disrupted it is very difficult to get all 3 components together for the outbound again. Pilots may be going out again on one flight and cabin crew on another and neither is often staying with the aircraft. Hence BA shorthaul is much worse affected than any other airline on days of disruption at LHR and domestics in particular end up getting cannibalised to protect international, the theory being that there is alternative transport, even if only by rail or even coach. At this time of year, with everything that moves being pretty well fully booked , several days of disruption on the trot takes a long time to unravel as passengers off cancelled flights go to the back of the queue for new bookings.To do otherwise would result in complete chaos. The deadline of Christmas makes the whole thing worse, and unlike normal periods of disruption there are few willing to just delay their travel plans. The next few days could be very difficult , with some high emotions.