I found this in the Wiltshire Arch Magazine (v59 - 1964). This is from long before the enclosure was spotted on aerial photos. Could it be just wishful thinking that it's the traces of another really old track focusing in on and passing by the site? Maybe it's just coincidence, and mere romanticism for me to posit such an ancient origin.
"In July 1962 Mr C N Tilley drew attention to a cropmark showing intermittently in corn for 2 miles and following roughly the 600ft contour line south of Savernake Forest from Durley to Langfield Copse, dropping down near Crofton Pumping Station and then winding up the hillside south of Wilton Brail. According to one of the oldest local inhabitants it was the line taken in his father's time by shepherds going from Cirencester to Weyhill Fair with their flocks."
It's certainly seems a memory of a long distance route (Cirencester to near Andover). How long does a route take to make an appreciable crop mark I wonder? Perhaps not long.
Whatever, Weyhill Fair was a major sheep fair held since... well since a ridiculously long time ago, according to the info at http://www.testvalley.gov.uk/Default.aspx?page=349
a website which also claims Weyhill is the crossing point between the Harrow Way (taking tin from Cornwall to Kent) and 'the Gold Road' bringing Irish gold through Holyhead down to Christchurch Bay.
Crofton's probably better known today for its beam engines and pumping station on the Kennet and Avon canal. But in the Neolithic it was a place with quite different significance. In 1976 the traces of causewayed-enclosure-style interrupted ditches were spotted on an aerial photograph. They completely encompass the village! It's possible you might be able to see something of them in the S/W stretches? The type of snail shells excavated tell us that at the time it was built the area was a clearing in woodland. The flints found confirm its Neolithic origins.
Apparently it has the largest? area of any known causewayed enclosure (600m across), and is also unusual in that unlike other causewayed enclosures - say, Knap Hill - it was built in a valley. Not only this, the River Dunn (now canalised) actually rose 'in the vicinity' of the enclosure, then flowing northeast into the Kennet at Hungerford. [This can't help but remind me of the proximity of the stream at Marden, but that's a henge and probably quite a different matter].
Another interesting point is that a Roman - or should that be, pre-Roman - road goes straight through the enclosure's centre. Another road crosses through at right angles (Avebury style). And following the southeasterly road a short distance brings us directly to a round barrow - surely confirmation of the roads pre-roman credentials?
I'm sure there will be little if anything to see at Crofton. But I hope people won't mind me mentioning it. It's really at the eastern end of the Pewsey Vale, which of course contains many other important prehistoric sites.
(see 'Excavation at Crofton Causewayed Enclosure' by Sue Lobb, in WAM v88 1995)
WAM 70-71 1975/6 notes that five long barrows lie within 6km of the enclosure, these on the higher ground to the S and SE, flanking the Vale of Pewsey.