Exeter Cathedral: 500 years old, nice and straight (a little parallax error in the picture). The yard in front of the Cathedral: less than 5 years old, seriously wonky. They couldn't even get it flat.
I see. That makes sense. I was picturing the largest pieces as being more like 400mm long, and being thrown by an explosive force, but the pattern didn't seem like it could have been caused by an explosion. It's a good image!