Chris, an Oxford friend who helped me with some research on outdoor education for the book shared these photographs of his trip and this note:
“Prompted by your work on your book last year we made our first camper trip of the season to Snowdonia this week. Although, we thought it spring, on the Mawddach, the season was still Winter. Here are some photos of us and friends en route, we actually completed the circuit of Cadair Idris Cwm which was a first for us”
That Cader Idris Cwm is in fact Cwm Cau on the south side of the summit ridge.