From the northern bank of the lake [at Ugbrooke], a long and steep ascent extends to a richly wooded and high ridge of land, called Mount Pleasant, on which is an ancient encampment, surrounded with a trench, and overhung with oaks, and other forest trees; its shape is elliptical; and tradition ascribes it to the Danes. The prospect from this eminence is noble and extensive; the local beauties of Ugbrooke combining with the romantic scenery of the surrounding country. The Park contains about 600 head of deer. Many of the oak and other trees are of uncommon magnitude, and shoot their branching arms to a stupendous height and distance.
Unfortunately the OS map makes the fort and hillside look pretty bereft of trees today. From p106 of The Beauties of England and Wales, Or, Delineations, Topographical, Historical, and Descriptive,... By John Britton. 1802.