I was on 207 course and, yes, we had to climb Pen Y Fan. There must have been road access to get all the tents up to the camp site, and there was a (cold) stream nearby. My best guess would go for the valley 345 degrees, 1.2 nm from the Pen Y Fan marker on Google Earth, with "Stricker's Hill" directly to the north-east. Makes me cold and tired to even think about it.