After scouring the Ordnance Survey app. for possible routes, I came across this one, which I believe was in the Trail magazine in September 2021. It only gave the route to the top of Mynydd Graig Goch so, to save retracing my steps, I descended firstly east then south before turning east again to reach the road back to the car park at the end of the valley.
Cwm Pennant is an amazingly peaceful little valley, the end of which is reached via a single track road and by opening (& closing obviously) 3 farm gates. This is sheep country and no mistake!