Tell-tale pale patches on a Knapweed (Centaurea nigra) leaf revealed a larval case of Coleophora paripennella, which has only 9 previous Carms records, 8 of them from Pembrey. I hope others will look out for this species, but beware that a couple of other Coleophora also feed on Knapweed so please photograph the case.
Hoverflies provided the rarest species of the day: the fantastic red-banded Brachypalpoides lentus, a scarce deadwood species that I have only seen once before (in Oxfordshire 15 years ago) and which has only a handful of previous Carms records. A Dasysyrphus venustus was also a nice surprise, but a male Sphaerophoria with an ambiguous lateral band was best left unidentified without dissection. I think/hope the beetle Malachius bipustulatus is distinctive, but I'm not 100% sure.
Finally, this large-headed bee looked interesting and distinctive, but I'm totally clueless on Hymenoptera. Perhaps someone can ID it, at least to family.