Aglaostigma aucupariae
This species is supposed to be associated with bedstraws but so far I've only found it on other plants. The first few were all on White Dead-nettle.
Aglaostigma aucupariae, North Elmham Cathedral Meadows (Norfolk, UK), 25th March 2020
Aglaostigma aucupariae, North Elmham Cathedral Meadows (Norfolk, UK), 25th March 2020 (different individual)
Aglaostigma aucupariae, North Elmham Cathedral Meadows (Norfolk, UK), 19th April 2021
This one was on Alder:
Aglaostigma aucupariae, Wendling Beck Environment Project (Norfolk, UK), 14th May 2022
There were three together on this Garlic Mustard - 2 on the top of the leaf (with a fly in the first photo) and one hidden below. I'm not sure if the one I retained for ID is the same as one of the two in the first photos or not.
2-3x Aglaostigma aucupariae, Wendling Beck Environment Project (Norfolk, UK), 29th April 2023
This was in the same area as the last.
Aglaostigma aucupariae showing forewing (including close-up of intercostal vein), scutellum and hind tarsal claws, Wendling Beck Environment Project (Norfolk, UK), 8th April 2024