(59) Stones (SY 58 NE; 59658688), two recumbent and partially buried sarsens, lie 5 yds. apart 350 yds. W. of Hampton Barn on top of Portesham Hill at 650 ft. above O.D. and on gentle slopes down to N. and E. They measure 10½ ft. by 4 ft. and 7½ ft. by 3 ft., the larger lying to the N. These two stones are probably the only remains of the 'collapsed dolmen' illustrated in Dorset Procs. XXIX (1908), lxxiv. The photograph, in which four or five stones are visible, suggests a collapsed chamber with a large tilted capstone. Crawford listed this as a long barrow orientated N.W. to S.E., with the two stones presumably as the remains of a chamber at the S.E. end, but there is now no evidence for this. Just to the N. is a probable round barrow, Portesham (44). (LVG I; O.S. Map of Neolithic Wessex, no. 144; G. E. Daniel, P.C.T.E.W. (1949), 235.)
Remains of alleged Neolithic long barrow also interpreted as two recumbent and partially buried sarsens with a probable Bronze Age bowl barrow to the north. The monument has suffered plough damage; the stones were intact and in position in 1990 but by June 2006 they had gone and the monument appeared only as a slight circular rise in the field.
(SY 59648689) "?Destroyed dolmen - both fallen. Mound to NW". (1)
Two large stones, perhaps at the E end of an otherwise destroyed chambered long barrow. Probable E-W orientation. (2)
(SY 59648689) Long Barrow (NR). (3)
Two recumbent stones, each with a NE-SW orientation. The stones lie 6.0m apart; both are of conglomerate; the W stone is the
larger and is approximately 3.0m long, 1.5m wide, with 0.6m visible above ground level. The E stone is 2.0m long, 1.0m wide
and 0.5m above ground level. 10.0m to the NW of the western stone is a grass covered mound 17.0m in diameter and 0.5m high. There is no other evidence of a mound connected wth the stones, and although this mound is mutilated it tends to give a NW-SE orientation to the long barrow. Side ditches are not discernable. (4) (SY 59628687) Stones (NAT). (5)
SY 59658688. These stones and mound are listed by OGS Crawford in the Map of Neolithic Wessex (a) as a long barrow orientated
NW to SE, with the two stones presumably as the remains of the chamber at the SE end, but there is now no evidence for this
(8). Instead RCHM describe the site as two recumbent and partially buried sarsens with a probable ?bowl barrow to the N.
The two stones are probably the only remains of a 'collapsed dolmen' illustrated in Authy 6, which is described by Daniel
(7) as of doubtful authenticity. The photograph which illustrates them shows four or five stones and suggests a
collapsed chamber with a large tilted capstone. The probable barrow to the N is about 67ft diameter, 21/2 ft high and has
been much ploughed. (6-8)
Portesham I. Long barrow listed by Grinsell (9), with an amendment (10) quoting the RCHM. (9-10)
SY 595867. Long barrow 300 metres west of Hampton Barn at the top of Portesham Hill. Scheduled. (11-12)
The stones were intact and in position in 1990 but by June 2006 they had gone and the monument appeared only as a slight circular rise in the field. 
The site lies in an area of set aside in the corner of an arable field. The remains comprise a very slight, ovoid mound, orientated N/S, 23m long, 20m wide and 0.3m high. It is difficult to ascertain whether this is the remains of a ploughed over round barrow or long mound. The stones described above remained until the early 21st century, when they were removed and possibly buried by the edge of the field (information from EH Historic Environment Field Adviser) (14).
The site was surveyed using differential GPS at a scale of 1: 200 as part of a survey of the long barrows on the South Dorset Ridgeway carried out by English Heritage and the Ridgeway Survey Group (15).