Found together with an identical further insectt on the underside of a pitfall trap. Much moisture present
No interactions present.
This is no flatworm. It's a slug, but I can't say which at present. Hopefully someone will know.
It has two eyes, one on the end of each of the large tentacles.
Lat/Lng: 51.3529, 0.08258
OS grid ref: TQ451635