A chain reveals itself
The Thames that runs through the centre of London is tidal. It means during certain points in the day her banks are exposed and beaches revealed. Many of these are accessible, if you’ve got your wits about you, and they offer unusual views of some of the river’s iconic landmarks.
Low tide also exposes some of the detritus that ends up on major river beds.
How long this chain had been left to rot I don’t know. What it was used for isn’t obvious. Whether someone will take it away or not, well that’s a complete mystery.
Which is all part of the fun.