2007 Excavation IV - Stonehenge - Research - Archaeology - The University of Sheffield: "The Cuckoo Stone
About 500m west of Woodhenge is the Cuckoo Stone, a squat sarsen boulder which lies on its side. A large trench was excavated around it to reveal the hole, immediately to its west, in which the stone originally sat. The shape of the hole closely matches that of the stone when recumbent and, as with the nearby Bulford standing stone excavated in 2005, it seems most likely that the Cuckoo Stone lay in this position as a natural feature before it was set on end as a standing stone.
Before the Cuckoo Stone was erected, it was removed from the solution hollow which had formed beneath it. A posthole was then dug into the base of the solution hollow. Finally, the stone was set vertically within the hole, replacing the wooden post. Unfortunately there was no dating evidence for this construction sequence but prehistoric features in its close vicinity suggest that this happened before 2000 BC....
The Cuckoo Stone compares well with the Tor Stone at Bulford, about a mile east of the River Avon. In 2005 excavations demonstrated that this stone was similarly associated with an Early Bronze Age cremation burial – in this case a double Food Vessel burial. It too had been raised from its natural recumbent position which was visible as a solution hollow."
It is very possible that the Heel Stone and Station Stones are also local but their original lying places has not been found so the jury is still out.
There is no evidence of any large number of Sarsen Stones anywhere on Salisbury Plain so I remain convinced the vast majority of the Sarsens came from the Marlborough Downs.
(There are other Cuckoo stones across Britain, odd erratics that seem out of place..)