In fading light yesterday afternoon I finally managed a follow up visit to Radyr Quarry, having looked at the southern end of the quarry face in December (see here). I only managed to access a relatively small area at the northern end and this was similar in character to what I found before, with quite a bit of Leiocolea turbinata on soil-capped ledges and a few small patches of Eucladium verticillatum. Only two additional taxa were found, Trichostomum crispulum (which was common) and a Conocephalum species. I've only seen C. conicum in my local area but this patch had a distinct salebrosum look to it. The thallus has distinct grooves on the dorsal surface, as seen in the photos below.
I wasn't 100% sure from this feature alone, so I also checked the hyaline cells at the thallus margin which, according to the Szweykowski et al. paper which first separated the two species (available here), should be 1-2 rows wide in conicum and 3-4 rows wide in salebrosum. In the photo below (click to enlarge) they are mostly 2 cells wide.
So this does appear to be salebrosum, though I'd like to have some fresh conicum to hand for comparison. As far as I know all the previous VC41 records since these species were split in 2005 have been from northern NPT, RCT and Merthyr Tydfil, so this site would be a bit of an outlier.
George, seems you are still missing some records from your version. Updated maps of Conocephalum taxa as follows: