Barry took several photos of tracks: these are crossing the pond and another photos shows them going into the ravine. I am not entirely sure what they are, although definitely not fox tracks. From the pattern, they look almost like giant vole tracks :-).

Chris suggests they could be ermine tracks, and that is a good possibility, as we certainly have these guys at the garden. Without seeing the tracks in situ, it is a bit hard to say, but ermine sounds good.