I brought home a few promising-looking samples from Seven Sisters, and sure enough two of them have the distinctive toothy leaves of Splachnum ampullaceum. These were in a very large (20+ hectare) grazing unit located on a failed spruce/larch plantation (SN8308), now fenced to enable cattle grazing to improve the habitat for Marsh Fritillay.
Also on the pats was a patch of what I can only assume is Pohlia nutans. Is this remotely feasible on a cow pat? Cells were elongated throughout the leaf, leaves are unbordered with a dentate apex and up to 4mm long at the tips of the stems, with dense rhizoidal tomentum below.