Of course, it might have been afterwards. This was!
In the end she got fed up with him hanging on and used her superior strength to get rid of him. She rotated about her axis until his head was upside down. At that point he let go. I was so interested I didn't take a picture until snap no4 in my original post. I could almost imagine you can see the compression marks at the back of her skull.
Incidentally I haven't seen any slow worms at all since. Just the male stag beetle again this afternoon