On Friday I made a third visit to the Ty-du arable fields at Capel Llanilltern, but much to my frustration the Phaeoceros rosettes still hadn't produced any horns. There were plenty of horns on the scattered plants of Anthoceros agrestis, but the many Phaeoceros plants were either sterile or else had male organs only. However, there were some clear differences between the plants and I suspect both Phaeoceros species are present. There were some completely sterile rosettes (top left photo) and some with dense male organs (top right); I suspect these are female and male plants of the dioecious P. laevis. There were also plants with more scattered male organs (bottom left and right photos), like the ones I photographed on my previous visit and which Sam thought might be P. carolinianus. I've brought a few rosettes home to incubate in the hope of coaxing these slow developers into producing horns!
George - your bottom-left photo has at least one young archegonium, appearing as a small lump. I have annotated it, as well as a couple of antheridial pits on the same thallus. It is P. carolinianus, whilst the first two photos are indeed male and female P. laevis.
All this left me only 45 minutes to poke around in St David's Churchyard at Groes-faen (ST071808). The only species of note among the 37 taxa recorded was Gyroweisia tenuis, tiny plants of which were growing in crevices of the west-facing wall of the church. Photos below - I hope others agree with the diagnosis as it's not a species I'm familiar with. The leaf tips varied in their bluntness between plants, but were mostly quite rounded.
The visit boosted the tetrad total (ST08Q) from 56 to 69 taxa.