In a valley to the east of Philpots Promontory Camp wanders the ghost of a Black Dog. A poacher in the area has said : "There's one thing I dare not do; I'd be afear'd to walk through that girt valley below Big-On-Little after dark. It's a terrible ellynge place and a gurt black ghost hound walks there o'nights". Ellynge is a local Sussex word for eerie and the hound is called "Gytrack" which is very similar to the "Guytrash" found in the north of England. Ian Hannah notes that the valley "seems to have no name (except that it is locally known as the Grattack, after a dog)".
This is taken from the Sussex Archaeology and Folklore website - Ian Hannah's article on the camp is in SAC Vol. 73 (156-167) 1932. http://www.sussexarch.org.uk/
Philpots Camp is a triangular promotory fort that uses the natural cliffs to the south west and south east for defence. On the north east side there's a bank and ditch to cut the fort off on its sandstone spur of the High Weald. But possibly more excitingly, the overhanging rocks of the cliffs were used much earlier, as rock shelters in Mesolithic times. A lot of flint knapping evidently went on here, and many pieces of flint were found at a large rock called variously 'Great upon Little' and 'Big upon Little'. Geology and weather have created that 'precarious undermined boulder' look - hence the name. According to this page at 'Sussex Archaeology and Folklore' http://www.sussexarch.org.uk/saaf/philhill.html :
"The stone was a great attraction for tourists at some point and there are initials carved wherever a hand could reach, dating anywhere from the 17th century, with initials being carved over others and the effects of the weather leaving the possibility of earlier dates, indeed Thomas Pownall in 1778 tell us that the stone "was covered with multitudes of names and initials of all dates". The top of the rock next to it is easily accessible allowing the brave to jump across to the top of Big-Upon-Little. The author of this page found copper coins left there like some sort of votive offering."
I also found this, which mentions the stone.
A man of 84 years of age told me that he had seen a book which told all about the rock called Great-upon-Little, but that it did not mention what he had heard people say, that the rock had formerly been an object of worship, and to touch it was death. (1905.)
p 163 in
Scraps of Folklore Collected by John Philipps Emslie
C. S. Burne
Folklore, Vol. 26, No. 2. (Jun. 30, 1915), pp. 153-170.
Were local people such as the man above responding to speculation they'd heard from people who'd found flints, etc, or local antiquarian's ideas? Or were they responding directly to the strangeness of the geology - something akin to Julian Cope's and some modern archaeologists' ideas of 'proto temples' and 'sacred landscapes'?
The webpage above has a photo of Great upon Little, and pf another stone with carvings and folklore - the ominously named 'Executioner's Rock'.
In the parish of West Hoadley, about three or four miles south of East-Grinsted, the ground in many places rises in high ridges with craggy cliffs. About half a mile west of West Hoadley church, there is a high narrow ridge covered with wood. The edge of this is a craggy cliff composed of enormous blocks of sand-stone. The soil hath been intirely washed from off them, and in many places from the interstices by which they are divided. One perceives these craggs, with bare broad white foreheads; and as it were, overlooking the wood which cloaths the valley at their feet.
In going to the place I passed across this deep valley, and was led by a narrow foot-path almost trackless, up to the cliff, which seems as one advances to hang over one's head. The mind in this passage is prepared with all the suspended feelings of awe and reverence; and as one approaches this particular rock standing with its stupendous bulk poised, seemingly in a miraculous manner, on a point, one is struck with amazement.
The recess in which it stands hath, behind this rock, and the rocks which surround it, a withdrawn and recluse passage, which the eye cannot look into but with an idea of its coming from some more secrete and holy adyt.
All these circumstances in an age of tutored superstition would give even to the firmest minds the impressions that lead to idolatry.
I make no doubt that if the Druids had resided in these parts, but that they would have adopted and consecrated this our Great upon Little, as one of their mysterious rocks, one of their symbols of the Numen, whom they taught the people to worship. Other priests also of the northern people might have done the same. The object itself would inspire, and the nature of the place where it is found would conspire to this imagination...
From Thomas Pownall's article called 'Account of a singular Stone among the Rocks of West Hoadley, Sussex', in Archaeologia v6 (January 1782).