In reply to Longsufferingropeholder:
Interesting. Quite a few photos on the net with the draws in place. One on instagram from 2016 which is the oldest I can find.
Some pics show an obvious crack just next to the bolts.
Forgotten drytool project perhaps?
Edit. In the link you post it looks like more than one line has been bolted. The one in the room you mentioned plus what seems like another which has a rope running through some draws in what looks like a different part of the roof.
Post edited at 20:20