UKC Logbook Description
Start from top of Pinnacle Ridge. Looking up, Porcupine Ridge is the left of two buttresses in front of the summit when looking up to the skyline. From the starting point, ascend the steep, wet gully on the left of the large Buttress above. Continue past some smaller, mossy, heathery lumps to the cleaner rock ridges above. The route begins in the middle of the first few "spines", and gains the broken triangular face.
The full route description can be found in Steve Ashton's revised 2017 scrambling guide as "Route 2 Braich Tŷ Du Face".