I noticed that this thread was referenced from the other jacking thread, and I then saw the picture above. That is NOT the rear jack point that the Bentley manual suggests to use.
The point in this picture is the flimsy support bar that is just in front of the muffler. It's only about 1 inch square tubing, and doesn't appear to be very substantial.
The Bentley manual suggests using the rear axle support, which is directly between the rear wheels. It also has two bolt heads a couple of inches apart that attach the rear sheet metal brace, similar to where this picture is taken. But it is on the axle support, which is FAR more substantial and is tied directly into the car's "frame".
edit: after following the "rainy day" link in that post, the picture is supposed to be from a Bentley event. However, that's not what the manual shows (to the best of my memory), and it's defintely not how I did it. I'm traveling right now, or I'd have a look at the manual again. I remember it showing the axle support to be the jack point, where the metal cable loop runs through. You can see that in a picture further down the page. Someone have a Bentley manual and want to take a look? Otherwise, I'll be home Friday night.