It's Birch woodland, so the obvious candidate is Birch Sawfly. But all the web images have yellow legs and antennae. So I'm wondering about Honeysuckle Sawfly?
No identification made yet.
No interactions present.
Honeysuckle Sawfly seems to looks very different from your specimen - e.g. see http://www.ispot.org.uk/node/353521
Steve (who knows very little about sawflies so probably wrong).
BMIG website: www.bmig.org.uk (centipedes, millipedes & woodlice)
BMIG Newsletters ~ www.bmig.org.uk/view/resource/bmig-newsletter
BMIG Bulletins ~ www.bmig.org.uk/view/resource/bmig-bulletin
Seem almost as variable as Ichneumon wasp photos - I suspect that several are incorrectly identified.
A photo of mine, also identified as Birch Sawfly (Woodwalton Fen, a few miles from this site), also lacks yellow on the antennae. I'm drifting back to that species, but far from certain.
It is not Cimbex femoratus, but might well be Arge ustulata or similar.
Looks quite possible, but really not sure myself.
Lat/Lng: 52.4877, -0.2339
OS grid ref: TL200892
Birch Woodland on peat