Epicaecilius pilipennis
Sounds like this might not be too common, though it's hard to find accurate up to date information about its status.
I found this while sitting at my desk when it landed on my hand, and I used the key at the Barkfly Recording Scheme website to identify it. It was 2.5mm long (front of head to apex of wings).
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Epicaecilius pilipennis, North Elmham (Norfolk, UK), 10th June 2024