I parked on the minor road to the south and walked up the bank and onto the edge of the field where the Long Barrow lies. Unfortunately the field was still full of crop (wheat) and as I didn't want to cause any crop damage I viewed from afar.
All I could see was the raised hump of the Long Barrow which was covered in scraggy long grass.
A short distance to the west of the Long Barrow are two Round Barrows (marked on O/S map – SP132263).
I had the same problem regarding the crops, so again I viewed from the edge of the field. The two Barrows were easy enough to spot, covered in trees and bushes.
Not much of interest to say about this long barrow. It lies like an island in the middle of a large arable field next to a minor road just over 2 miles west of Lower Swell. I walked up the tractor tracks in a field of wheat to reach it. No megaliths are exposed.
On my way back to the road, I startled a deer hiding in the wheat, which didn`t bound very far away. Shortly afterwards, I was startled by a fawn jumping out of the crop in front of me.
Just to add some more detail - The longbarrow at Cow Common is (rather interestingly?) made of small stones, and it is oriented east-west, with views to south and east. It was your typical Cotswold Severn longbarrow design, with a false entrance in a forecourt flanked by extensions of the mound. The mound was surrounded by a dry stone wall. It had two actual chambers: the NE chamber had remains of 3 skeletons, with five more just outside. The second chamber 10m from the eastern end contained two adults and one infant, and two flint flakes. James Dyer's 'Southern Britain' mentions some Neolithic pottery spoons too (surely very unusual?). One of the chambers was oval with a carefully corbelled roof. A Roman coin was also found at the western end of the longbarrow - was it just lost, or deliberately buried for some reason?
The area was reused later, or perhaps in constant use, as the longbarrow became surrounded by the ten round barrows in the barrow cemetery. Five form an overlapping row to the west and were opened in 1874. The most southerly had a cist burial and two urn burials. The second had a beehive-shaped chamber inside, approached by a long 6m passage - other corbelled chambers are known from this area of Gloucestershire so perhaps it was a local burial 'fashion' for a while? The other three barrows in the row held cremations that seem to have been interred in cloths, secured with bone pins.
(info from Dyer's book above, and the MAGIC website)