The smaller stone here has been so regularly shaped that it would be impossible to tell if it had a prehistoric origin. The larger stone is a difficult one to call as far as I’m concerned, it may be prehistoric but has been tooled on one face and at least one side with the face bearing an inscription from 1784. The barrow is also a little suspicious due to it’s size and the fact that although it’s marked as tumulus on the map it doesn’t appear in my copy of the SMR.
Scratch head and file under Hmmm....