The root of their problem is their failure to secure Union agreement for pilots (other than on the first transit of the day) and cabin crew to treat LHR as just another transit airport so the crews have (different) minimum base turnaround times so that they can come off the aircraft, go and have a coffee and a bun, ring Mum or whatever. Hence the aircraft, pilots and cabin crew are all rostered separately through LHR and do not stay together for their complete shift as do most and especially Easyjet and Ryan whose shorthaul systemwide punctuality knocks the socks off BA.
Skylion talks through his a*se. There is no such issue with BA Pilots. BA shorthaul pilots (for that is who we are talking about) routinely stay on board the aircraft for LHR transits until their shift is complete - indeed it was my, and most of my colleagues, preference to do so rather than have to rely of ureliable transport to and from the Central Area facility.
No, cabin crew are a different animal and indeed are stuck on the 1980's when it comes to working agreements and are only now starting trials (for an extra payment
of course) of staying with the aircraft on an LHR transit. Furthermore I understand that this will apply only on the middle day of a 3 day trip (day 2 will only consist of 2 flights btw). It will not apply on a 3 sector day 1 or day 3 (not that they do many of those anyway).