Olibrus affinis
The Olibrus that I've found most often at the Cathedral Meadows is corticalis, and, partly because of that and partly because under the microscope this insect looked paler than it did in life, I was expecting this to be another corticalis. But despite my best efforts I couldn't see the microsculpture on most of the elytra, and I was pretty sure I didn't find it that hard to see on previous corticalis. There was some sinuous linear microsculpture towards the apex especially near the suture, as is described for affinis (and a couple of other species). The aedeagus clinched it for me, and it was only then that I realised that I had in fact recorded affinis at this location previously. The species is associated with Goat's-beard, Catsear and Smooth Catsear, the first two of which grow at this location, but this one was found on a Dandelion flower.
male Olibrus affinis showing its elytra (twoards the apex, suture side), aedeagus (side view and flat, latter with internal part to left), North Elmham Cathedral Meadows (Norfolk, UK), 4th June 2021
The previous one was a female. There are differences between the species in female genitalia, but these are quite subtle.
female Olibrus affinis showing its ovipositor, North Elmham Cathedral Meadows (Norfolk, UK), 7th August 2019
I labelled this one incorrectly at the time, but I'm not sure if I misidentified it or just got it mixed up with something else. Anyway, the photo of the genitalia appear to confirm that it should have been labelled as affinis.
male Olibrus affinis showing aedeagus (flat and side views), North Elmham Cathedral Meadows (Norfolk, UK), 19th August 2020