Kim, you are very bad!
The business doesn’t need to know anything about survey points. They just need somebody to build an extension or mark the boundaries or whatever. The actual process is irrelevant to them.
Maybe it has been there for years, you've just not noticed it before.And the business is not necessarily the same as the landowner.
A business can commission some work to be done on their property that requires a survey and yet they don’t know about the existence of survey points.
As Wombat and LWAB ( but not Kim!) say.It's just a masonry nail and a washer to stop it being hit too far in. Also known as a mickey pin.https://www.toolstation.com/mickey-pin/p28729Ideal for using to hang pictures on plastered walls.
<ob-facebook> It's a marker left by pedobears to denote children ripe for abusing nearby. Pass it on or Bill Gates will fry your BRANES with 5G gene therapy. </ob-facebook>