What a little gem this is, so close to the road too!
I noticed something interesting in the next field that got me excited, something I haven't seen mentioned before anywhere. In the next field south of the tomb there is a set of large stones in a rough line very close to one another. The middle stone has a very clear U shaped groove in it and on each side is a large boulder. If you stand on the south end and look through the groove from where the south boulder is, your looking straight at the tomb above! If you look from the north end (from the tomb entrance direction) the groove points directly at a notch in the horizon where two hills meet. Very intriguing. This tomb, as has ben pointed out before, is unusually aligned north-south.
See the image above for a view looking northish at the tomb.
I spent quite some time here, scanning the tomb and scanning the countryside for something that would make the little red dots on the OS map make sense. Too many thornbushes and too little time..