Inexplicable

This is one the most perplexing things I have seen. Somehow this screw has been stuck standing up into the sill of the living room windows to Al and Nat's flat. They are on the first floor, well out of reach of the ground floor, and there is a waist height bar across the windows preventing anyone reaching down to do this from inside. Answers on a postcard please.


Pentax P30n, 50mm, f/5.6 @ 1/125s, Ilford Pan 400