GeoGraph - photograph every grid square

This old granite milestone is on the opposite corner verge to the modern milepost at Longcross crossroads [which is unusual in that it is a north-south-east-west junction]. It's been recently painted, but why does it have the old fashioned broad arrow mark that signifies that it was once Government property ? The carved names point to Lansallos village to the south, and to what seems to be Lerryn village in a westerly direction.