Very distinctive blue underside.
No interactions present.
Very useful to have the photo of the underside, and I think there is enough detail shown to rule out a third similar species, Anoplotrupes stercorosus (which has fewer ridges on the hind legs). However, I can't quite see enough to choose between G. stercorarius and G. spiniger, although my guess would be for the former species.
See previous discussion at:
See also a more detailed description and image from the Watford Coleoptera Group:
(The WCG website has lots of useful information, the home page is http://www.thewcg.org.uk)
Entomologist and biological recorder
Lat/Lng: 49.9, -6.4
OS grid ref: SV8815