I had time to visit this site today, there is some doubt as to it's being a barrow, Grinsell seems to think it natural. Given the name and its appearance it looks ok to me, I don't know whether Grinsell visited the barrow, although he did get to see a great many. Anyway as it is today only the landward side in the photo is still in good condition, the seaward side having fallen away at some time. From it can be seen the nearby Sandy barrow on a hilltop about a quarter of a mile inland to the north. Behind can be seen the Island of Portland several miles to the southwest.
"Goggin's Barrow. Applies to a prominent mound situated on edge of cliff about 15 chains northwest of Osmington Mills; supposed to be of ancient British construction" (3). (2,3) A natural mound with an east-west diameter of 16.0 metres, and a height of 0.6 metres. The mound is grass covered on the north, but the south half has been eroded, exposing its formation of 0.3 metres of topsoil upon a strata of shale. (4) Coggins Barrow on cliff edge, is natural. (5)