Found under the plywood as seen above. Woodland habitat, very damp, 10M from water.
The insect is a Spider mite, Damaeus onustus . I honestly did not see it at the time.
No interactions present.
Looking at my notes I estimated 30mm at the time. Looking again it appears that, that was a bit of an over estimation, closer to 20mm is nearer. The mite is a good indication of the leeches length, it being ≈2mm.
An iSpot Project- HELP WITH IDS - UK & Ireland Community - PLANTS
...move to inverts more help there :)
Thanks for the nudge..
Lat/Lng: 53.2076, -0.5576
OS grid ref: SK964688
Boultham Park Woods, Lincoln