I have every sympathy for the BA crew...but there again I have managed to get the wheels of a large civil aeroplane on the grass whilst taxying at a US airport, albeit one of their Military ones.
My excuse?...it was night and raining so the flight deck side windows were slightly obscured. I kept well away from the blue taxyway lights when making a sharp left turn and felt more than a little surprise when I realised that my left wheels were on the slightly damp green stuff.
I later found out that the taxyway lights were not set on the edge of the tarmac, but several feet into the grass, so the picture was right but not the actuality.
Unlike the BA crew, all my incident required was a little spade work from the Flight Engineer, a large piece of PSP to stick on front of the left wheels and we were soon back on dry land. He later told me that he had been based at that particular field and knew that the shovels and PSP were stored in a small shed next to the taxyway as pilots managed to use the grass on a regular basis at night.
Bad lighting?...a regular event?....but still embarrassing!