It looked like a dog. I didn't actually see anything, mind.
[Palm Sunday] gatherings at Deverill took place on Cowdown, i.e., the ridge, parallel with the road from Sutton; boys, as well as men, went up to "beat the ball", i.e. play trap.
"When was the last time?"
"Oh! when I were a bit of a buoy, they gied over then, 'cos of 'en seed the devil; I were up there, but I didn't see en', but a were there like a girt dog, and a did rin about, and the chaps rinned away; I seed em rin, and I rinned too; 'twere gied over ater that."
On Palm Sunday there were gatherings on Longbridge Deverill Cow-down to play "trap," going up by "Jacob's ladder." The young men, with the elders to watch them, would "beat the ball" up Cow-down and then play trap.
And on Palm Sunday the women and children would go out into the fields "to tread the wheat." (1897)
Folklore Notes from South-West Wilts
John U. Powell
Folklore, Vol. 12, No. 1. (Mar., 1901), pp. 71-83.
Cow Down does have an example of a defended Iron Age settlement, and archaeologists have found the remains of round houses there, together with artifacts relating to everyday life, like chalk loom weights.
The hill it tops is the obvious and overriding view from the Neolithic henge near its base. As such I find it tempting to say it had some significance for the people who used and made the henge
You can see a photo of Cow Down from the henge at Deverill Road here.