Well and truly ploughed down, and fenced off from the plebs, this was once one of the long mounds flanking the eastern terminus of the Dorset Cursus. Alas, it is not doing well any more.
Grinsell claimed to have found it in 1938, when its ditches were "well-marked", and then noted that in 1954 when he came to write up "Dorset Barrows", it was ploughed to the edge of the mound. Sadly the tractors and harvesters and muckspreaders now go straight over the top of this integral part of our national heritage. He notes it as 95 feet long, 70 feet wide [which makes it oval more than long] and 3.5 feet high.
In "A Landscape Revealed", Martin Green says:
During Colt Hoare's brief examination of this mound he described it as 'surrounded by sarsen stones'. Indeed, even now [book published 2000] I have noticed large lumps of sarsen ploughed to the surface around the edges of this mound.
A Neolithic long barrow, listed by RCHME as Pentridge 23 and by Grinsell as Pentridge III. Located immediately west of Bokerley Dyke and a short distance north of the northeastern terminal of the Dorset Cursus (Linear 41). RCHME were intiially uncertain as to whether or not this mound was in fact a long barrow, largely because of the extent of plough damage, though it was noted that Grinsell had observed side ditches, these also being visible on air photographs. At the time, RCHME measured the mound as being 95 feet by 70 feet, aligned broadly southeast-northwest, and 4 feet high. Subsequently RCHME (in Bowen 1990, 1991) confirmed identification as a long barrow with large side ditches. Bowen (1991) also identified this mound with one dug into by Cunnington and Hoare in the early 19th century, based on Hoare's published description and map of sites in the vicinity. Both Grinsell and RCHME had previously assumed that Hoare was referring to a round barrow (unnumbered by RCHME, but listed as Pentridge 13d by Grinsell). Hoare described the mound as being surrounded by large sarsen stones. His finds were purely Saxon, relating to an intrusive 7th century burial. Within the mound, he found a small hook, a buckle and a clench bolt, plus an ivory ring (representing a bag or pouch). Below was an extended female inhumation, near the head of which were two further clench bolts. Grave goods included a biconical gold bead, 2 glass beads, one of them threaded on a gold wire ring, a jet bead, and a millefiori plaque suspended from a gold chain. The ornaments have been suggested to represent the remains of a rich necklace and linked pin suite, while the iron objects have been suggested to represent the surviving traces of a bed or similar structure on which the corpse was interred.