Lack of customers due to the state they are in.
BA are trying to cut costs by reducing staff and are using the move to T5 to try (as a by product of the move) to do that, the staff know that and are therefore concerned about their jobs and are of course unhappy, which even unintentionally filters down to the customers - I personally do not find BA very customer friendly now and although I liked to fly BA in the past now they come across to me as just the same as any other airline - I have flown United the last three times I have flown across the Atlantic.
Alex Ford