So there's calls to 'turn back and land', and have strict protocols for storage of bodies? Get this understood- once you turn back and let the Police make a meal of it, that crew are probably not going to complete the flight, getting standbys out takes hours, and the flight is probably not going anywhere. There are no protocols- it is up to the crew to handle it pragmatically. Sometimes you can put bodies in the lavatories, though with relatives on board it's not a viable option. There is no alternative to leaving them in a seat, suitably covered. If you were to ask the passengers 'we've had one stiff on us, shall we go back and land or continue to your destination?', there would be a unanimous show of hands for 'well they're dead already, we might as well carry on.'
People die. They are inconsiderate enough to do it on aeroplanes sometimes. All airlines suffer this, not just BA. They all do the same. Get over it, it happens. It's not all BA's fault. There was nothing else the crew could do.