I used to work in BD crewing (it was that long ago) and apart from the fun & games with the 'heathrow shuffle' which was aimed at getting pax out on time and stopping BA pinching them, I recall occasions like an F/O who would call up and say the cat had been run over and the missus very upset so he couldn't do the evening Belfast !! So that's why you sometimes get daft calls at 1050 ahead of an 1100 standby....