Cefn Isaf sits in a field, which at the time of my visit was completely overgrown. The sun shone down and we chilled here for a while - Mrs IM commented that the site looks just like a Megalithic bus-stop. The capstone is huge as is the slab at the back of the chamber.
We started here, intending to take the path up to Ystumcegid. When we reached the concrete bridge between the two sites found that it was closed. It definitely wasn't worth the risk, so we turned back - vowing to return to see Ystumcegid another day.
An old photo of Cefn Isaf by Alvin Langdon Coburn. There's a second photo, also by Coburn, on the same web site. Sadly neither are dated, but were probably taken in the first half of the 20th Century.