Cleaning an Anchor

As I raced back to the office following a session observation today I did a double take to see our Collections Care Officer with a hose pipe, a drain and an anchor. Apparently our CEO (ex 2nd Sea Lord) wants the anchor, found in the Bathhouse mud. I wonder what he is going to do with it? Anyway, this is how to clean an anchor that has been embedded in mud for many years!
The extra is the shot I took of Peter, bent over the drain with his brush and hose pipe. Can anyone shed light on why my extras rotate?