No, I'm not sure! But it's about 6-7ft tall and stands out of line with the hedge (in other words the hedge isn't built flush with it) and of a nicely tapering shape. It's not a gatepost, as there are no access points into the fields there and I couldn't see any sign of holes or that either hinges or a bolt had been affixed to it. Mind you, it was June, so vegetation may have obscured that kind of thing.
But no, I have no way of knowing if it is just a stone in a hedge! :-)
If you're in the area, perhaps you might have a look? Happy to be shown up as wishful thinking!
I believe this stone is called Bosiliack standing stone in the booklet - Ancient sites in west Penwith by Cheryl Straffon [ very good ] and the real map ref is SW43693423. It says in booklet "In hedge of lane to ding dong mine, 1.8m [5 3/4 ft]", so it certainly sounds like the same stone, i'm sure the one i saw was the same as the one in your photo, when i saw it i didn't know it was in books either.
Yes, it is that one (I'll change the NGR). It wasn't in the previous edition of "Ancient Sites", but I noticed it had been added to the recent re-print. I'd be quite interested to know if its addition to the revised version was in any way due it being added on here!