There are earlier sources we can look at - the tithe map for St Twynnells parish (c.1840), and an even earlier map from a Stackpole Estate map book (c.1782). Extracts from these maps are shown below.
The road south from the church had yet to be improved, and the lane past the farm takes a different path to that today. It maybe, of course that the tithe map is incorrect, because on an earlier estate map from c1786, the road appears to pass to the east of the old building, not to the west, as on the tithe map above.
Perhaps the Loveston stone was part of a gateway into the farm?