Finally got to visit this one and to be honest I wouldn't recommend it.
First off while it's just off the old A1 and there is parking close by the woodland between the barrow and the road is jungle like with no clear paths - not an easy 100m to get through.
Second when you get there, there is very little to see. A semi-circle has been cut in the woods and the records show this as the site of the barrow but there is nothing obvious there - through there is a clear ring of bracken growth so the soil is obviously different. You'd need a full day with an industrial strimmer to see any features.
Thirdly the site is close to the A1 so there is lots of noise and very little atmosphere.
All that being said there are some points of note:
1) This barrow hasn't been built to be seen from a distance. It's not prominent at all and seems to have been located here either because it was close to water (stream nearby) or close to an ancient trackway. It does lie on raised (slightly) ground.
2) There might be a second barrow in the field between the trees and the A1 (or the original position might have been out and this is the barrow). This looks like an over-ploughed feature on top of a raised area of land - roughly 50m from the marked site.
Both can be seen from the A1 if you are passing but don't blink or you'll miss it.
On the way back through the trees I came across what looked like a large piece of worked stone - 1m or so in all directions, roughly rectangular and looked like it had split at some time. Not sure what this is/was but it stands out as an "erratic" in that it's very large and has no obvious context. It's on the north edge of the woods near the stream as you work back from the barrow to the old A1. Photos attached.
"In August, 1921, a cist was excavated by Mr. Bosanquet and his son in the parish of Rock. The site is the plantation known as Heiferlaw Plantation on the old edition (Sheet 27, S.W.), and Ellsnook Wood on the new edition (Sheet 29, N.W.). In the cist was found a beaker. The cist was in the top of a mound, and it is thought that it is not the primary interment. The
mound is certainly partly artificial. Excavations are to be resumed this summer. (Mr. R. C. Bosanquet, Rock Moor, Alnwick)."