After getting drenched and lost twice after finding the 'other two' cairns I'm glad to report to such happenings during this visit did not happen. Making sure I couldn't find this site by difficult routes, in the past, I found the cairn by a much easier route.
Parking in the same place as the other two I continued walking south until a crossroads in the tracks. Headed east for at least three meters and continued south on a deer trail. Keep looking east until the top of the hill can be seen in a clearing. The cairn is easily spotted as a 'bump' on top. This cairn was much larger at some point but now is 7 meters wide and almost 1 meter high. Some earthfast rocks on the edge of the cairn suggest kerbs but it would be fair to say this site has taken a battering. Somehow it survives and with the growing darkness feels old, atmospheric and peaceful lost amongst the trees and time.
Not much to look at but a special place all those years ago, and for me a special place on a Friday night, totally worthwhile.