Detritus 1

A piece of galvanised steel detritus gathered on one of my walks in mid-December last and which is now established in a spot underneath the kitchen window.

Believed to be a socket for some sort of a fence to be erected around a flat-bed lorry. The sturdy black headed handle rotates the upper lug, presumably allowing for insertion and locking - into something.

Thought to have been posted at the time, but search fails to reveal it.