Boundary marker stud

My other iPhone photos were not interesting so I was going to post this and ask if anyone knows what it is. But then a web search revealed it is a boundary marker stud, usually marking the boundary between private and public land. I am not sure what it is doing at this road junction, but I went out again to get a photograph of it in context. Extra shows a typical Upminster front garden with vehicles. The stud is at the bottom right. 
Boundary marker studs may be more common in the City of London, for example, where photographers have to decide which side they are on (Stand Your Ground (Grant Smith)
I found a blog post on these markers which was very helpful. Tim Whitton: The art of the boundary marker stud
There may be a future for me in recording more suburban details - I had toyed with and rejected dropped kerbs as a subject. 

Another term to search for is 'demarcation'. There are interesting speculations here: ppprune
It may mark the location of pipes. Who knows?