Found this whilst out walking last week. Not totally convinced that it isn't a rubbing post but...
It is a large stone for a rubbing post, about 4ft high and around 2 ft wide.
It lines up nicely with Brown Willy.
Why erect a rubbing post when ther are walls, trees and barns nearby.
It is natural in shape, ie has not been cut by man.
To look for yourself take the footpath from the east end of Davidstow Airfield, very muddy at Oldpark end. Once past the barns at Oldpark turn right down wide track, the stone is in the field on the right.