So here we were, scrabbling around in a space that felt about 6 inches square when someone said, "Does this route have a 'grade' - like in climbing?" "Oh yes, it's grade two" replied our instructor Andrew. "And what do they go up to?" "Grade five". In which case I could only assume that the people who can manage a grade five route had a mole and an earthworm for parents. As well as scrabbling we were also, crawling, shuffling, scratching, creeping and butting our way along one of the labyrinth of passageways in Eglwys Faen cave which penetrates deep into the heart of the Llangattock Escarpment in the Brecon Beacons.