I found this empty carapace on a pile of weed dredged from the lake
No interactions present.
Definitely a crayfish, and I think it is a Signal Crayfish - rostrum ('head') has parallel edges, claw has a whitish spot at the hinge (I believe this is what constitutes its "signal"). Size would have been useful to know as well.
Entomologist and biological recorder
Thanks, David. So this lake has signal crayfish and zebra mussels!
University of Edinburgh and Biodiversity Observatory (OU)
Lat/Lng: 52.014194900551, -0.70984125137329
OS grid ref: SP886358
Approximate location for various observations