On a recent visit to the Nympsfield long barrow, I noticed this one marked on the OS map, so decided to pay it a visit.
Shortly after turning onto the minor road leading to the village of Nympsfield from the B4066, I drove into a National Trust car park on the left which serves Woodchester Park (you have to pay to park here, although I didn't notice until I was leaving).
The footpath from the car park leads you down into a wooded valley. Where the path turns to the right, along the valley, I carried straight on up the other side, through the trees and out onto the end of a gliding club's airstrip.
The barrow lies at the western end of this grass airstrip. It's been ploughed over, in the past, and is now no more than 2 metres high, with no visible stones.