I rather wonder if the fort at Camp Hill is the site for the following folklore. There is a 'Keys to the Past' page about the fort though it doesn't seem much is known about it. I can tell from the map that you would seem to get to it by walking up Clayport Bank. And Swansfield Park is the name of the golf course in which the fort now resides. But maybe someone from Alnwick would know.
.. on moonlight nights these tiny folk trooped out of dell, and cavern, and mine, and from beneath the bracken, and from under green knowes, and out of other lonely places to hold their revels, with music and dance, in the Fairies' Hollow at the top of Clayport Bank.
On one occasion, while visiting Alnwick, Mr. Tate pointed out to me the Fairies' Hollow at the head of Clayport, and a series of steps, or rather little benches, caused by subsidences of the soil, rising in a gentle gradient to Swansfield Gate, which had obtained the name of the "Fairy Steps."
From the Denham Tracts - the first paragraph he has copied from Tate's History of Alnwick.
I found George Tate writing about the Fairies' Hollow elsewhere. I can't help thinking he's writing autobiographically! as it's curiously imaginative otherwise...
The fairies, it is said, have been dead and were buried at Brinkburn many a long year ago. This, however, will apply only to the Brinkburn community, for in other localities the belief in the "good folk" has lingered on even into the present century. Some forty years ago, or more, we had near to Alnwick, the Fairies' Hollow, on the top of Clayport bank. At that period a boy who, having drunk more deeply than was perhaps good for him out of the wells of imaginative literature, stole away from his bed on a moolit night, and ensconsed among the rocks overlooking the hollow, waited and watched till the "witching hour of night" to catch a glimpse of the fairies tripping out of the caverns and hills. The grass waved to and fro by a gentle breeze, and the pale light flickered over the hollow, as fleecy clouds sailed over the moon; imagination was excited, aided, it may be, by the "foure-levit clover" hidden in his cap, and troops of green-clad tiny elves appeared to swarm over the hollow, and to join in the mystic mazes of the dance. Soon, however, darker clouds obscured the moon, and threw a shadow over the scene; the illusion was dispelled - the vision melted away - and the boy reluctantly returned home to his bed, to dream of fairy land.