Any sensible pilot on a plane for more than a few months knows the 'right' weights he should be seeing on a loadsheet, and a glance at the fuel figures is all that is needed. You point to errors that have occurred in this process- as far as I am aware it has not happened anywhere where I have flown. I think the system is sufficient, and any such errors are gross negligence.
So this thread rumours idiocy or serious error afoot in BA. I have just said I would like to see more evidence please. The reason would be far more likely late reassignment of a fuelled aeroplane to a 25 minute flight, but I'm afraid as pointed out, as it currently stands, there would be no circumstance I can see where such events as outlined here would happen. It would mean the 747 must have departed at max take-off weight for a 25 minute flight to Cardiff.
I simply say put up or shut up, but don't denigrate an innocent party with these nonsense rumours without anything substantial.