Hahnia nava
This was found in a pitfall trap in grassland and assuming I've identified it correctly looks like it's pretty uncommon in Norfolk away from the Brecks. The similar Iberina montana has much in common - I think I've ruled that out on a combination of external appearance and palps but I welcome correction or confirmation from any more experienced spider-botherers.
male Hahnia nava showing one palp (5 views) and the other palp (2 views), Wendling Beck Environment Project (Norfolk, UK), 17th-18th May 2023