Lesteva longoelytrata
This wasn't the easiest beetle to key with a few couplets where I wasn't quite sure and had to try both ways. In the end though it ended up with this common species of Lesteva. The elytra were only a little more than twice the length of the pronotum but that seems to match online photos, though I'm not convinced it isn't matched by some species where they're meant to be shorter or the same as twice the length of the pronotum, assuming the photos online are correctly labelled. Taking the puncturing into account I think we're safe calling this longoelytrata, though if I'm honest, had this been a rare species I would have been hesitant to name it confidently. There seems to be quite a bit of variation in colour with many online photos not so dark-legged, but there are enough matching mine for this not to concern me. Note that my specimen was a bit faded when I came to examine it, so the close-up photos are paler than it was before I foolishly stored it in a sunlit location.
Lesteva longoelytrata showing head, maxillary palp, pronotum and impression at base of hind corner of pronotum, North Elmham Cathedral Meadows (Norfolk, UK), 30th April 2019