Hi Doug
I’ve been working on the same one and ran into the same problem as you. I think it’s Cheilymenia pulcherrima (although the spores are a bit big. EDIT: they are OK in other sources). I collected it from sheep dung, so I think we both get a record according to Tom’s rules…
Ref:http://www.ascofrance.com/recolte/2545/pezizomycetes-pezizales-pyronemataceae-cheilymenia-pulcherrima#
However, there are 10 species in the UK but I don’t have access to this key http://www.sciencedirect.com/science/article/pii/S0953756296801705