Double-U Long-palp Tipula unca
I think the combination of wing pattern, abdomen pattern and thorax pattern (note pale central stripe) is probably sufficient for this ID but it was reassuring to see the little notch in the dorsal edge of tergite 10 which clinched it.
female Double-U Long-palp Tipula unca showing wing and abdomen tip from side, Wendling Beck Environment Project (Norfolk, UK), 21st June 2024
This disappeared after I took the first photo below. I think it was probably the same one that reappeared a bit later but can't be 100% sure.
female Double-U Long-palp Tipula unca showing wing and abdomen tip from side, Wendling Beck Environment Project (Norfolk, UK), 14th July 2024