I was told that BA had a lot of long haul flights in the air - looking now at Heathrow Flight Arrivals there are a host that landed after 22:00 - LA, Mumbai, Calgary, Miami, Vegas, Denver - theres Honkers due at 04:00 etc etc.
I reckon BA just fronted up to the failed Govt and said "stuff you Pal we're on our way"............. looking at this it confirms it
http://news.bbc.co.uk/1/hi/world/europe/8631429.stm "18:32 BA tells the BBC it still plans to land more than a dozen long-haul flights that are currently en route at Heathrow, despite the fact airspace over southern England remains closed. It is unclear what conversations have been taking place between BA and Nats"